A multi-chlorine washable antibacterial cotton-resistant fabric for medical care clothes and a preparation method thereof

Abstract

The application relates to the technical field of textile modification, and discloses a multiple chlorine washing resistant and antibacterial cotton fabric for medical and nursing clothes and a preparation method thereof, which comprises a pure cotton fabric, amino acid modified halamine precursors grafted on the pure cotton fabric and loaded zinc doped copper oxide nanoclusters. The back of the pure cotton fabric is coated with a color developing coating liquid composed of polylactic acid microspheres embedding 3,3',5,5'-tetramethylbenzidine and a water-based polyurethane fixing agent. The preparation method comprises the steps of alkali treatment, precursor and L-lysine grafting, mixed salt in-situ coordination precipitation, coating and curing and chlorination activation. The application builds a multi-contact crosslinking network on the surface of the cotton fiber through the amino acid modified halamine precursors, cooperates with the lattice defects generated by the zinc doped copper oxide nanoclusters, and improves the sterilization activity. The color changing response of the color developing agent protected by the microspheres to the active chlorine is utilized to realize intuitive identification of the antibacterial performance margin, and the problems of antibacterial component loss and invisible antibacterial state are solved.

Description

Technical Field

[0001] This invention relates to the field of textile modification technology, specifically to a reusable, washable, antibacterial, and cotton-resistant fabric for medical and nursing care garments, and its preparation method. Background Technology

[0002] Medical gowns serve as a physical barrier against the spread of pathogens in medical settings, and cotton fabrics are the primary material for these gowns due to their moisture absorption and breathability. Since bacteria and viruses easily adhere to the surface of cotton fibers, providing cotton fabrics with durable and renewable antibacterial properties is a requirement in the medical protective field.

[0003] Currently, grafting halogenated amine precursors onto cotton fabrics and activating them with chlorine-containing detergents is the main approach to regenerating antibacterial properties. However, the chemical bonding force between existing halogenated amine precursors and the hydroxyl groups on the surface of cotton fibers exhibits instability under repeated washing cycles. This causes the antibacterial components to gradually detach from the fiber matrix with increasing washing cycles, reducing the number of cycles required for antibacterial activity regeneration. Furthermore, single halogenated amine antibacterial systems experience fluctuations in bactericidal rates when facing complex pathogenic bacterial populations, affecting the reliability of the protective effect.

[0004] Furthermore, healthcare workers cannot visually determine the active chlorine content on the fabric surface during use. When antibacterial activity decreases below the effective protection threshold, the lack of a clear monitoring and feedback mechanism creates blind spots in protection. This invisibility of antibacterial efficacy decay, along with the loss of antibacterial components during chlorination, limits the protective safety and lifespan of antibacterial cotton fabrics in high-risk medical areas.

[0005] Therefore, this invention proposes a reusable, washable, antibacterial, and cotton-resistant fabric for medical and nursing care garments, and its preparation method, to address the shortcomings of existing technologies. Summary of the Invention

[0006] The purpose of this invention is to provide a reusable chlorine-washable antibacterial cotton-resistant fabric for medical and nursing care garments and its preparation method, which solves the problems of insufficient stability of the binding between halogen amine precursors and cotton fibers, resulting in the loss of antibacterial components, limited improvement of bactericidal efficiency, and lack of intuitive means to identify the remaining antibacterial performance.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] The first aspect of this invention provides a reusable, washable, antibacterial, and cotton-resistant fabric for medical garments, comprising the following components:

[0009] Pure cotton fabric, amino acid-modified haloamine precursor grafted onto the surface of pure cotton fabric, activated form of amino acid-modified haloamine precursor, and zinc-doped copper oxide nanoclusters loaded on pure cotton fabric.

[0010] The amino acid-modified haloamine precursor is formed by a stepwise grafting reaction of 3-(3-chloro-2-hydroxypropyl)-5,5-dimethylhydantoin and L-lysine.

[0011] The pure cotton fabric is coated with a color-developing solution on one side of its back, and the color-developing solution is cross-linked and cured. The color-developing solution consists of polylactic acid microspheres encapsulating 3,3′,5,5′-tetramethylbenzidine and an aqueous polyurethane fixing agent.

[0012] 3-(3-chloro-2-hydroxypropyl)-5,5-dimethylhydantoin covalently bonds to the hydroxyl groups on the cellulose fibers of pure cotton fabric through the active chloroalkyl groups in its molecular structure. L-lysine enters the system as a modifier, and through further reaction with the amino group and the haloamine precursor molecule, it constructs a multi-contact cross-linked network on the fabric surface, enhancing the fixation strength of the haloamine groups and providing a chemical stability basis for repeated chlorination.

[0013] Zinc-doped copper oxide nanoclusters were anchored on the surface of pure cotton fabric grafted with amino acid-modified haloamine precursors via in-situ coordination precipitation. The doping of zinc ions altered the lattice defects of copper oxide, thereby enhancing the electron transfer rate during the antibacterial and antiviral process.

[0014] The intelligent color development function is based on the redox response of 3,3′,5,5′-tetramethylbenzidine to active chlorine. Polylactic acid microspheres serve as an encapsulation carrier, delaying the oxidative damage of the color developer caused by environmental factors. A water-based polyurethane fixing agent firmly locks the polylactic acid microspheres onto the back of the fabric. When the multi-washable antibacterial cotton fabric used in medical gowns is activated with sodium hypochlorite, the halogenated amine groups are converted into an N-Cl structure with antibacterial activity. Simultaneously, the released trace amounts of active chlorine induce a color change in 3,3′,5,5′-tetramethylbenzidine, enabling visual monitoring of the antibacterial efficacy.

[0015] A second aspect of this invention provides a method for preparing a reusable, washable, antibacterial, and cotton-resistant fabric for medical protective clothing, comprising the following steps:

[0016] Pure cotton fabric is treated by immersing it in a sodium hydroxide solution. The treatment temperature is 45–55℃, and the treatment time is 20–30 minutes. The pure cotton fabric is then removed and washed with water until neutral, resulting in activated pure cotton fabric. The concentration of the sodium hydroxide solution is 0.3–0.5 mol / L. Alkali treatment disrupts some of the hydrogen bonds in the cotton fibers, increasing the reactivity of the surface hydroxyl groups.

[0017] Activated pure cotton fabrics were immersed in a mixed alkaline solution for reaction. The concentrations of the mixed alkaline solution components were as follows: 0.08–0.15 mol / L for 3-(3-chloro-2-hydroxypropyl)-5,5-dimethylhydantoin, 0.08–0.12 mol / L for sodium carbonate, and 0.04–0.06 mol / L for sodium hydroxide. The pH of the mixed alkaline solution was controlled at 9.0–10.5. The reaction was carried out at 45–55℃ for 2.0–3.0 h.

[0018] Then, L-lysine at a concentration of 0.01–0.02 mol / L was added to the mixed alkaline solution, and the reaction continued for 25–35 minutes.

[0019] The activated pure cotton fabric after the reaction was washed with water, neutralized to pH 6.0-7.0 with acetic acid at a concentration of 0.03-0.08 mol / L, and dried to obtain pure cotton fabric grafted with amino acid-modified haloamine precursor.

[0020] Pure cotton fabric grafted with amino acid-modified haloamine precursors was immersed in a mixed salt solution for rinsing. The total concentration of the mixed salt solution was 0.04–0.06 mol / L, consisting of zinc nitrate and copper nitrate, with a zinc ion molar fraction of 0.05–0.15. The rinsing rate was maintained at 60%–80%.

[0021] Subsequently, the fabric was immersed in a sodium hydroxide solution with a concentration of 0.04–0.06 mol / L at room temperature for in-situ coordination precipitation. After washing with water and drying, an antibacterial and antiviral pure cotton fabric loaded with zinc-doped copper oxide nanoclusters was obtained.

[0022] A color-developing coating solution was prepared by uniformly mixing polylactic acid microspheres embedded with 3,3′,5,5′-tetramethylbenzidine with an aqueous polyurethane fixing agent. The mass ratio of polylactic acid microspheres to aqueous polyurethane fixing agent was 1:2 to 1:4. The color-developing coating solution was applied to the back side of an antibacterial and antiviral pure cotton fabric loaded with zinc-doped copper oxide nanoclusters. Crosslinking and curing were carried out at 145–155℃ for 2–4 min to obtain an unactivated antibacterial and antiviral pure cotton fabric.

[0023] Unactivated antibacterial and antiviral pure cotton fabric is immersed in a sodium hypochlorite standard solution for washing to induce an activation reaction. The sodium hypochlorite standard solution has an effective chlorine concentration of 400–600 mg / L and a pH of 5.5–6.5. The activation reaction time is 20–40 min. After rinsing until no chlorine odor remains and drying, a reusable, washable, antibacterial, and cotton-resistant fabric suitable for medical gowns is obtained.

[0024] In summary, the present invention has at least one of the following beneficial technical effects:

[0025] 1. This invention constructs a multi-contact crosslinking system on the surface of pure cotton fabric through a stepwise grafting reaction of 3-(3-chloro-2-hydroxypropyl)-5,5-dimethylhydantoin and L-lysine. This multi-contact crosslinking system enhances the chemical bond strength between the haloamine precursor and the cotton fiber, ensuring that the antibacterial components in the reusable antibacterial cotton fabric used in medical protective clothing are not easily detached after multiple cycles of washing and activation, thus maintaining the regenerative capacity of the antibacterial properties.

[0026] 2. This invention loads zinc-doped copper oxide nanoclusters via in-situ coordination precipitation. Zinc ion doping alters the crystallization state of copper oxide and generates lattice defects. Combined with the oxidizing environment provided by the amino acid-modified haloamine precursor, this optimizes the electron transport pathway of the reusable, washable, antibacterial, and durable cotton fabric used in medical gowns during the killing of bacteria and viruses, thereby enhancing the bactericidal reactivity.

[0027] 3. This invention achieves visualization of the antibacterial state by coating polylactic acid microspheres containing 3,3′,5,5′-tetramethylbenzidine on one side of the back of pure cotton fabric. The polylactic acid microspheres protect 3,3′,5,5′-tetramethylbenzidine from external environmental interference. Utilizing the redox color-changing reaction of 3,3′,5,5′-tetramethylbenzidine on the N-Cl structure formed after activation by sodium hypochlorite, the invention provides a direct identification function for the remaining antibacterial performance of washable, antibacterial, and durable cotton fabrics used in medical garments. Attached Figure Description

[0028] Figure 1 This is a line graph showing the change in active chlorine content of fabrics with the number of washes in Examples 1 to 3 and Comparative Example 1 of the present invention;

[0029] Figure 2 This is a dual-axis trend distribution diagram of the metal element loading in the fabrics of Examples 1 to 3 of the present invention;

[0030] Figure 3 The graphs showing the relationship between the color change response time and total color difference of the fabrics in Examples 1 to 3 of this invention are shown.

[0031] Figure 4 Line graphs showing the retention rate of warp breaking strength of fabrics in Examples 1 to 3 and Comparative Example 1 as a function of the number of chlorine washes.

[0032] Figure 5 This is a graph showing the evolution of the long-lasting antibacterial properties of the fabrics in Examples 1 to 3 and Comparative Example 1 of the present invention;

[0033] Figure 6 This is a graph showing the evolution of the total color difference of the fabrics in Examples 1 to 3 and Comparative Example 2 as a function of the number of washes.

[0034] Figure 7The graph shows the relationship between the relative proliferation rate of fabric cells in Examples 1 to 3 and Comparative Example 3 of the present invention and the culture time. Detailed Implementation

[0035] The following is in conjunction with the appendix Figure 1 -Appendix Figure 7 The present invention will be further described in detail below.

[0036] Examples 1-3:

[0037] Example 1:

[0038] This embodiment provides a method for preparing a reusable, washable, antibacterial, and cotton-resistant fabric for medical protective clothing, comprising the following steps:

[0039] Take 40-count pure cotton fabric (110g / m²) 2 The cotton fabric was immersed in a 0.3 mol / L sodium hydroxide solution and treated at 45°C for 20 min. The cotton fabric was then removed and washed with water until neutral to obtain activated cotton fabric.

[0040] Activated pure cotton fabric was immersed in a mixed alkaline solution containing 0.08 mol / L of 3-(3-chloro-2-hydroxypropyl)-5,5-dimethylhydantoin, 0.08 mol / L of sodium carbonate, and 0.04 mol / L of sodium hydroxide. The pH of the mixed alkaline solution was controlled at 9.0, and the reaction was carried out at 45°C for 2.0 h. Then, 0.01 mol / L of L-lysine was added to the mixed alkaline solution and the reaction was continued for 25 min. The reacted fabric was washed with water and neutralized to pH 6.0 with 0.03 mol / L acetic acid. After drying, pure cotton fabric grafted with amino acid modified haloamine precursor was obtained.

[0041] Amino acid-modified haloamine precursor-grafted pure cotton fabric was immersed in a mixed salt solution containing zinc nitrate and copper nitrate with a total concentration of 0.04 mol / L (where the molar fraction of zinc ions was 0.05) while maintaining a water-rolling rate of 60%. Subsequently, it was immersed in a 0.04 mol / L sodium hydroxide solution at room temperature for in-situ coordination precipitation, washed with water and dried to obtain antibacterial and antiviral pure cotton fabric loaded with zinc-doped copper oxide nanoclusters.

[0042] Polylactic acid microspheres encapsulated with 3,3′,5,5′-tetramethylbenzidine were mixed with an aqueous polyurethane fixing agent at a mass ratio of 1:2 to prepare a color-developing coating solution. The color-developing coating solution was coated on one side of the back of an antibacterial and antiviral pure cotton fabric loaded with zinc-doped copper oxide nanoclusters, and then baked at 145℃ for 2 minutes to crosslink and cure, thus obtaining an unactivated antibacterial and antiviral pure cotton fabric.

[0043] Unactivated antibacterial and antiviral pure cotton fabric was immersed in a sodium hypochlorite standard solution with an effective chlorine concentration of 400 mg / L and a pH of 5.5 for 20 minutes to activate the reaction. After rinsing until there was no chlorine odor and drying, a multi-chlorine washable antibacterial cotton fabric for medical protective clothing was obtained.

[0044] Example 2:

[0045] This embodiment provides a method for preparing a reusable, washable, antibacterial, and cotton-resistant fabric for medical protective clothing, comprising the following steps:

[0046] Take 60-count pure cotton fabric (130g / m²) 2 The cotton fabric was immersed in a 0.5 mol / L sodium hydroxide solution and treated at 55°C for 30 min. The cotton fabric was then removed and washed with water until neutral to obtain activated cotton fabric.

[0047] Activated pure cotton fabric was immersed in a mixed alkaline solution containing 0.15 mol / L of 3-(3-chloro-2-hydroxypropyl)-5,5-dimethylhydantoin, 0.12 mol / L of sodium carbonate, and 0.06 mol / L of sodium hydroxide. The pH of the mixed alkaline solution was controlled at 10.5, and the reaction was carried out at 55°C for 3.0 h. Then, 0.02 mol / L of L-lysine was added to the mixed alkaline solution and the reaction was continued for 35 min. The reacted fabric was washed with water and neutralized to pH 7.0 with 0.08 mol / L acetic acid. After drying, pure cotton fabric grafted with amino acid modified haloamine precursor was obtained.

[0048] Amino acid-modified haloamine precursor-grafted pure cotton fabric was immersed in a mixed salt solution containing zinc nitrate and copper nitrate with a total concentration of 0.06 mol / L (where the molar fraction of zinc ions was 0.15) while maintaining a water-rolling rate of 80%. Subsequently, it was immersed in a 0.06 mol / L sodium hydroxide solution at room temperature for in-situ coordination precipitation, washed with water and dried to obtain antibacterial and antiviral pure cotton fabric loaded with zinc-doped copper oxide nanoclusters.

[0049] Polylactic acid microspheres encapsulated with 3,3′,5,5′-tetramethylbenzidine were mixed with an aqueous polyurethane fixing agent at a mass ratio of 1:4 to prepare a color-developing coating solution. The color-developing coating solution was coated on one side of the back of an antibacterial and antiviral pure cotton fabric loaded with zinc-doped copper oxide nanoclusters, and then baked at 155℃ for 4 min to crosslink and cure, thus obtaining an unactivated antibacterial and antiviral pure cotton fabric.

[0050] Unactivated antibacterial and antiviral pure cotton fabric was immersed in a sodium hypochlorite standard solution with an effective chlorine concentration of 600 mg / L and a pH of 6.5 for 40 minutes to activate the reaction. After rinsing until there was no chlorine odor and drying, a multi-chlorine washable antibacterial and cotton-resistant fabric for medical protective clothing was obtained.

[0051] Example 3:

[0052] This embodiment provides a method for preparing a reusable, washable, antibacterial, and cotton-resistant fabric for medical protective clothing, comprising the following steps:

[0053] Take 40-count pure cotton fabric (120g / m²) 2 The cotton fabric was immersed in a 0.4 mol / L sodium hydroxide solution and treated at 50°C for 25 min. The cotton fabric was then removed and washed with water until neutral to obtain activated cotton fabric.

[0054] Activated pure cotton fabric was immersed in a mixed alkaline solution containing 0.12 mol / L of 3-(3-chloro-2-hydroxypropyl)-5,5-dimethylhydantoin, 0.1 mol / L of sodium carbonate, and 0.05 mol / L of sodium hydroxide. The pH of the mixed alkaline solution was controlled at 9.8, and the reaction was carried out at 50°C for 2.5 h. Then, 0.015 mol / L of L-lysine was added to the mixed alkaline solution and the reaction was continued for 30 min. The reacted fabric was washed with water and neutralized to pH 6.5 with 0.05 mol / L acetic acid. After drying, pure cotton fabric grafted with amino acid modified haloamine precursor was obtained.

[0055] Amino acid-modified haloamine precursor-grafted pure cotton fabric was immersed in a mixed salt solution containing zinc nitrate and copper nitrate with a total concentration of 0.05 mol / L (where the molar fraction of zinc ions was 0.10) while maintaining a water-rolling rate of 70%. Subsequently, it was immersed in a 0.05 mol / L sodium hydroxide solution at room temperature for in-situ coordination precipitation, washed with water and dried to obtain antibacterial and antiviral pure cotton fabric loaded with zinc-doped copper oxide nanoclusters.

[0056] Polylactic acid microspheres encapsulated with 3,3′,5,5′-tetramethylbenzidine were mixed with an aqueous polyurethane fixing agent at a mass ratio of 1:3 to prepare a color-developing coating solution. The color-developing coating solution was coated on one side of the back of an antibacterial and antiviral pure cotton fabric loaded with zinc-doped copper oxide nanoclusters, and then baked at 150°C for 3 min to crosslink and cure, resulting in an unactivated antibacterial and antiviral pure cotton fabric.

[0057] Unactivated antibacterial and antiviral pure cotton fabric was immersed in a sodium hypochlorite standard solution with an effective chlorine concentration of 500 mg / L and a pH of 6.0 for 30 minutes to activate the reaction. After rinsing until there was no chlorine odor and drying, a multi-chlorine washable antibacterial cotton fabric for medical clothing was obtained.

[0058] It should be noted that in this invention, the sequential process of first performing initial etherification grafting of pure cotton fabric with 3-(3-chloro-2-hydroxypropyl)-5,5-dimethylhydantoin (halogen amine precursor) in an alkaline solution, followed by the addition of L-lysine for secondary modification, is called a stepwise grafting reaction.

[0059] Since the nucleophilic activity of the amino group in L-lysine is much stronger than that of the hydroxyl group on the surface of cotton fiber under alkaline conditions, this stepwise grafting process sequence can kinetically avoid preferential side reactions between the haloamine precursor and lysine, thereby improving the effective grafting rate of the haloamine precursor on cotton fiber.

[0060] In this invention, after the amino acid-modified halogen amine precursor grafted onto pure cotton fabric is washed and activated with sodium hypochlorite standard solution, the NH bond on its amide group is transformed into an N-Cl bond with strong oxidizing and antibacterial and antiviral activity. This chemical structure is referred to as the activated form in this invention.

[0061] Furthermore, in preparing unactivated antibacterial and antiviral pure cotton fabrics, this invention strictly controls the crosslinking and curing conditions of the color-developing coating solution to be baked at 145–155°C for 2–4 minutes. This specific process parameter window not only ensures that the water-based polyurethane fixing agent reaches sufficient crosslinking activation energy, forming a strong and tough network structure on the back of the fabric that can withstand multiple high-concentration chlorine washes, but also thermodynamically prevents the polylactic acid microspheres encapsulating 3,3′,5,5′-tetramethylbenzidine from prematurely leaking and failing due to exceeding their melting point. If the temperature is below 145°C or the time is too short, the coating's chlorine wash fastness will not meet the standard; if the temperature is above 155°C or the time is too long, the microsphere structure will undergo irreversible thermodynamic damage.

[0062] Comparative Examples 1-3:

[0063] Comparative Example 1:

[0064] Compared to Example 1, the difference lies in replacing the activation reaction in the first step and the grafting reaction in the second step with a conventional oxidative grafting process:

[0065] Take 50-count pure cotton fabric (120g / m²) 2 The sample was immersed in a 0.4 mol / L sodium hydroxide solution for 30 min at room temperature and washed with water. Then, it was immersed in a system containing 0.015 mol / L 2,2,6,6-tetramethylpiperidine oxide, 0.12 mol / L sodium bromide, and 0.4 mol / L sodium hypochlorite, with the pH controlled at 10.2 and the reaction at 4 °C for 35 min for oxidation. After washing, 1-(3-chloropropyl)-3,5-dimethyl-2,4,6-triazine-2,4,6(1H,3H,5H)-trione was added, and the reaction was carried out at pH 9.8 and 50 °C for 2.5 h. The sample was then directly washed with water and dried. No L-lysine was added for modification, and all other steps were the same.

[0066] Comparative Example 2:

[0067] Compared with Example 1, the difference is that in the fourth step of preparing the color-developing coating solution, no water-based polyurethane fixing agent is added. Instead, the polylactic acid microsphere dispersion containing 3,3′,5,5′-tetramethylbenzidine is coated on one side of the back of the antibacterial and antiviral pure cotton fabric loaded with zinc-doped copper oxide nanoclusters and baked at 150°C for 3 minutes. All other steps are the same.

[0068] Comparative Example 3:

[0069] Compared with Example 1, the difference is that in the second step, after activating the pure cotton fabric at 50°C for 2.5 hours, 0.015 mol / L L-lysine is not added to the mixed alkaline solution. Instead, the reacted fabric is directly washed with water and neutralized to pH 6.5 with 0.05 mol / L acetic acid and then dried. All other steps are the same.

[0070] Test Examples 1-7:

[0071] Test Example 1:

[0072] Accurately weigh 0.50g of pre-washed and dried fabric sample (including fabrics prepared in Examples 1, 2, 3 and Comparative Example 1), and use scissors to cut the test fabric into 2mm×2mm scraps.

[0073] Place the weighed shredded cloth into a 250mL iodine flask, add 50mL of distilled water and 25mL of 0.1mol / L potassium iodide solution to the iodine flask containing the shredded cloth, and add 5mL of 0.1mol / L acetic acid solution to adjust the reaction system to a weakly acidic state.

[0074] After sealing, place the iodine flask in a dark environment and let it stand for 30 minutes to ensure that the active chlorine fixed on the fabric surface fully reacts with the potassium iodide in the solution to release elemental iodine.

[0075] The mixture in the iodine flask was titrated with a 0.01 mol / L sodium thiosulfate standard titration solution. When the reaction solution turned pale yellow, 1 mL of 1% starch indicator was added. The sodium thiosulfate standard titration solution was added dropwise until the blue color of the system completely disappeared and remained unchanged for 30 seconds. The volume of sodium thiosulfate standard titration solution consumed was recorded. A blank control group without fabric samples was set up and the blank consumption volume was recorded. The active chlorine content per unit mass of fabric (mmol / g) was calculated by the difference in titration volume.

[0076] Fabrics prepared in Examples 1, 2, 3 and Comparative Example 1 were respectively put into a standard industrial washing machine for 2, 4, 6, 8 and 10 washing operations. After each washing cycle, the fabrics were dried and steps 1 to 4 were repeated. The changes in active chlorine content at each washing cycle stage were recorded.

[0077] Table 1. Test data of active chlorine content in fabrics in Examples 1 to 3 and Comparative Example 1

[0078] Sample Name 0 washes (mmol / g) Two washes (mmol / g) Four water washes (mmol / g) Six water washes (mmol / g) 8 washes (mmol / g) 10 water washes (mmol / g) Example 1 1.02 0.98 0.95 0.91 0.86 0.82 Example 2 1.15 1.11 1.05 1.01 0.96 0.91 Example 3 0.86 0.82 0.77 0.74 0.69 0.65 Comparative Example 1 1.05 0.74 0.46 0.23 0.11 0.04

[0079] Figure 1 The horizontal axis represents the number of standard industrial washes, and the vertical axis represents the active chlorine content measured per unit mass of the fabric. Solid lines, dashed lines, and dotted lines marked with circles, squares, and triangles correspond to the numerical trends of Examples 1, 2, and 3, respectively, while dotted lines marked with diamonds correspond to the numerical trend of Example 1.

[0080] The test results are as follows:

[0081] Based on the data in Table 1 and Figure 1 It can be seen that the pure cotton fabric prepared by the alkaline epoxy etherification process maintains a stable active chlorine loading state after multiple washes. In the conventional chemical processing environment of textiles, the type of covalent bond between the finishing agent and the fiber skeleton determines the wash resistance life of the functional layer. The initial active chlorine content of Examples 1 to 3 ranged from 0.86 mmol / g to 1.15 mmol / g. After 10 standard washing cycles, the test values ​​of each example remained between 0.65 mmol / g and 0.91 mmol / g.

[0082] The titration decay curves show a direct correspondence with the ether bond configuration specified in the synthetic route. The epoxy intermediate generated in situ in an alkaline medium from 3-(3-chloro-2-hydroxypropyl)-5,5-dimethylhydantoin preferentially undergoes ring-opening addition with the primary hydroxyl groups on the cellulose macromolecular chain due to the steric hindrance of the hydantoin ring. The ether bond network exhibits resistance to hydrolysis in weakly acidic to weakly alkaline washing solutions, preventing the loss of nitrogen-containing heterocyclic structures under mechanical abrasion and water flow impact, and ensuring that the N-Cl active centers remain intact on the fiber surface during multiple washing operations.

[0083] The test results of Comparative Example 1 reveal the limitations of the traditional oxidative grafting process in terms of durability. The initial active chlorine content of the fabric in Comparative Example 1 after preparation reached 1.05 mmol / g. After 4 water washes, the titration value decreased to 0.46 mmol / g, and after 10 water washes, the value decreased to 0.04 mmol / g.

[0084] Ester bonds formed by oxidative grafting reactions are prone to irreversible hydrolysis in aqueous environments. During the washing process, free water molecules attack the positively charged carbon atoms of the ester group, causing the active components with antibacterial properties to break off from the cotton fiber skeleton.

[0085] The destruction of the anchoring structure leads to irreversible loss of functional groups with each wash. Even with the addition of a sodium hypochlorite regeneration process, chloride ions in the solution cannot regenerate the antibacterial structure at the detached sites. Analysis of the differences in the curve trends of all samples shows that the etherification synthesis route based on in-situ epoxidation can resist chemical loss during the washing process, supporting the engineering application requirements for anti-wash dissipation.

[0086] Test Example 2:

[0087] Accurately weigh 0.2051g, 0.2013g, and 0.2038g of antibacterial and antiviral pure cotton fabric samples loaded with zinc-doped copper oxide nanoclusters after being shredded (corresponding to the intermediate stage fabrics prepared in Examples 1, 2, and 3, respectively). Transfer the weighing paper containing the shredded samples to a fume hood and pour the samples into a clean polytetrafluoroethylene digestion vessel.

[0088] Slowly add 6 mL of 65% concentrated nitric acid and 2 mL of 30% hydrogen peroxide solution to each digestion vessel, tighten the sealing cap of the digestion vessel, and place the sealed digestion vessel into the rotating plate hole inside the microwave digester.

[0089] The heating ramp-up program of the microwave digester was set to control the temperature inside the digestion chamber to rise uniformly to 180°C within 15 minutes, and maintain a constant heating state of 180°C for 25 minutes, so as to promote the complete oxidation and decomposition of the cellulose macromolecular skeleton and the metal compounds attached to the surface and convert them into dissolved inorganic salt solution.

[0090] After the microwave heating program is finished, wait for the digestion vessel to cool naturally to room temperature. Open the digestion vessel and transfer the internal solution to a 120°C heating plate for continuous heating to remove acid. Observe the evaporation state of the solution and stop heating when about 1 mL of clear liquid remains. Rinse the remaining liquid with water and transfer it to a 50 mL volumetric flask. Add deionized water to make up to the mark and shake well by inverting the flask.

[0091] Turn on the argon supply system of the inductively coupled plasma atomic emission spectrometer and light up the plasma generator. Then, introduce pre-prepared zinc and copper standard solutions with different concentration gradients in sequence to establish a linear working curve. Subsequently, the sample solution to be tested in the volumetric flask is introduced into the nebulizer through a peristaltic pump. The detector records the spectral signal intensity of the characteristic emission wavelengths of zinc and copper. The specific loading of zinc and copper elements per unit mass of fabric (mg / g) is calculated according to the linear working curve.

[0092] Table 2. Test data on the mass loading of zinc and copper elements in the fabrics of Examples 1 to 3

[0093] Sample Name Sample size (g) Zinc elemental loading (mg / g) Copper loading (mg / g) Zinc / copper mass ratio Example 1 0.2051 4.37 36.82 0.118 Example 2 0.2013 6.54 33.15 0.197 Example 3 0.2038 2.01 40.56 0.049

[0094] Figure 2 The horizontal axis represents the example number using different feeding parameters, the left vertical axis corresponds to the solid line with square markings, showing the loading mass of zinc on pure cotton fabric, and the right vertical axis corresponds to the dashed line with triangle markings, showing the loading mass of copper on pure cotton fabric.

[0095] The test results are as follows:

[0096] Based on the data in Table 2 and Figure 2 It is known that chemical bath coordination deposition can firmly bind target metal ions into the macromolecular network of pure cotton fabric in a specific ratio. In-situ coordination precipitation provides a reliable chemical pathway for the enrichment of metal components onto the surface of the base fabric.

[0097] In the preceding steps, the hydantoin ring structure grafted onto the cellulose matrix exhibits a strong coordination tendency. The nitrogen and oxygen atoms distributed on the hydantoin heterocycle contain lone pairs of electrons, which spontaneously capture free zinc and copper ions through coordination bonds when encountering a mixed salt solution. The subsequent introduction of sodium hydroxide solution disrupts the dissolution equilibrium of the metal ions.

[0098] As the local pH rises, the adsorbed and fixed metal complex ions are converted into hydroxides in situ and precipitate out. The heat from the baking process promotes the dehydration of the precipitated hydroxides, transforming them into stable zinc-doped copper oxide nanocrystal structures.

[0099] In Example 1, the zinc ion molar fraction was set at 0.10, and the actual mass ratio of zinc to copper in the finished fabric measured by the instrument was 0.118. Examples 2 and 3 changed the component ratios in the mixed salt solution, and the metal loading data exported by the analytical instrument showed a synchronous scaling correlation.

[0100] The concentration of metal ions in the solution formulation is accurately mapped onto the surface of the solid fiber. This chemical padding process, which avoids the need for complex electrochemical deposition equipment, is adapted to the standard dyeing and printing production line operation mode, ensuring component reproducibility during mass production of fabrics.

[0101] Test Example 3:

[0102] Accurately cut unactivated antibacterial and antiviral pure cotton fabrics with a size of 10cm×10cm (samples taken from Examples 1, 2 and 3 after the fourth step of the reaction), and lay each fabric sample flat on the test platform inside the standard D65 light source color matching box.

[0103] Turn on the portable spectrophotometer and perform white and black board calibration. Place the colorimeter probe vertically and firmly against the surface of the fabric to be tested, and continuously measure the initial colorimetric value L at 5 different locations on the same fabric surface. * a * and b * The arithmetic mean was taken as the background color data before contact with sodium hypochlorite solution.

[0104] Using a pipette, draw 0.5 mL of sodium hypochlorite standard test solution with an effective chlorine concentration of 500 mg / L and a pH of 6.0, and add it dropwise at a uniform rate to the center area of ​​the color-developing coating on the back of the fabric sample. Press the stopwatch to start recording the time the droplet contacts the fabric surface the instant it touches the surface.

[0105] Observe the color change of the area where the liquid droplets penetrate the fabric surface. Stop timing when the color of the area stabilizes and no longer undergoes visible color deepening. Record the time consumed in this process as the color change response time (s).

[0106] Point the probe of the portable spectrophotometer at the central test area after the color change has stabilized, and collect the colorimetric value L again. * a * and b * Based on the background colorimetric data, the total color difference of each sample before and after the reaction was calculated according to the CIE1976 color difference formula.

[0107] Table 3. Colorimetric test data of fabrics from Examples 1 to 3 upon exposure to chlorine.

[0108] Sample Name Initial L * Initial a * Initial b * After color change, L * After color change, a * After color change, b * Color change response time (s) Total color difference Example 1 88.2 1.1 3.4 55.4 -8.2 -32.1 12.5 49.2 Example 2 87.5 0.8 4.1 52.1 -10.5 -38.6 14.3 56.6 Example 3 89.1 1.5 2.8 58.9 -6.5 -28.4 9.8 44.1

[0109] Figure 3 The horizontal axis represents the test objects grouped using different coating formulations. The left vertical axis corresponds to the solid line with circular markings, showing the color change response time of the fabric after contact with the chlorine-containing standard solution. The right vertical axis corresponds to the dashed line with square markings, showing the total color difference value calculated after the color stabilizes.

[0110] The test results are as follows:

[0111] Based on the data in Table 3 and Figure 3 It is evident that the use of polylactic acid microsphere encapsulation combined with a waterborne polyurethane color-fixing system can effectively achieve rapid visual response to chlorine-containing disinfectants. In routine disinfection procedures in medical environments, healthcare personnel need to visually confirm whether the disinfectant has reached an effective concentration.

[0112] Initial b of Examples 1 to 3 * The value shows a slightly positive yellow tint, and after contact with sodium hypochlorite solution, b *The numerical value shifted negatively to the range of -28.4 to -38.6, indicating that the test area turned dark blue. The corresponding total color difference was in the range of 44.1 to 56.6, exceeding the normal recognition threshold of the human eye, thus providing a clear color change warning.

[0113] This chemical sensing response is based on a redox mechanism. 3,3′,5,5′-Tetramethylbenzidine is encapsulated within a polylactic acid shell, preventing premature failure upon contact with atmospheric oxygen. When an aqueous solution containing hypochlorous acid molecules is dripped onto the fabric surface, the active disinfectant penetrates the cross-linked network constructed by the aqueous polyurethane, seeps into the polylactic acid microspheres, and reacts with the color developer. Under strong oxidizing conditions, the 3,3′,5,5′-tetramethylbenzidine molecules lose electrons, transforming into a blue product exhibiting characteristics of a charge-transfer complex. The graph shows that the color-changing response time is concentrated between 9.8 s and 14.3 s, indicating an intrinsic correlation between the response speed and the formulation of the coating system.

[0114] Example 2 used a higher proportion of water-based polyurethane fixing agent. The increased crosslinking density lengthened the diffusion path of hypochlorous acid molecules to some extent, resulting in a relatively longer color change time. However, it also accumulated more color developer reserves, ultimately exhibiting a higher color difference value. The overall embedding and high-temperature curing process transformed the sensitive color developer into a stable sensing coating, meeting the practical requirements of monitoring the disinfection status of medical gown fabrics.

[0115] Test Example 4:

[0116] Sodium hypochlorite standard solution with an effective chlorine concentration of 500 mg / L and pH adjusted to 6.0 was measured and poured into the washing chamber of an industrial standard washing tester. Fabrics prepared in Examples 1, 2, 3 and Comparative Example 1 were respectively placed into the chamber. The standard washing program was run under the conditions of a set temperature of 40°C and a liquor ratio of 1:50. Fabric samples that were not washed (0 times), washed 5 times, and washed 10 times were collected respectively.

[0117] The collected fabric samples from each stage were placed in a standard constant temperature and humidity chamber at 20℃ and 65% relative humidity for 24 hours for conditioning.

[0118] According to the GB / T 3923.1 standard for testing the tensile properties of fabrics, the moisture-conditioned fabric is cut into strip-shaped test specimens with a length of 300 mm and a width of 50 mm in parallel along the warp direction using a cutting knife. The working width of the specimen is ensured to contain the complete warp structure by pulling out the edge yarns.

[0119] The strip-shaped test specimen is fixed in the upper and lower clamps of the universal testing machine. The initial clamping distance is set to 200 mm, the tensile speed is controlled to 100 mm / min, and the instrument is started to apply a continuous longitudinal tensile load to the specimen until the specimen breaks. The warp breaking strength (N) at the moment the fabric breaks is recorded.

[0120] Each group of samples was tested in parallel 5 times and the arithmetic mean was calculated. The warp breaking strength after 5 and 10 washes was divided by the initial warp breaking strength of the unwashed sample to calculate the warp breaking strength retention rate (%) of the fabric at each stage.

[0121] Table 4. Test data of warp breaking strength and retention rate of fabrics in Examples 1 to 3 and Comparative Example 1

[0122] Sample Name Heavy load (N) after 0 washes 5-wash intensity (N) Retention rate after 5 washes (%) 10 washes with intense (N) power Retention rate after 10 washes (%) Example 1 485.6 451.2 92.9 412.3 84.9 Example 2 471.2 425.8 90.3 382.7 81.2 Example 3 496.5 473.1 95.2 441.5 88.9 Comparative Example 1 391.4 285.3 72.8 186.2 47.5

[0123] Figure 4 The horizontal axis represents the number of cycles of washing in the sodium hypochlorite standard solution, and the vertical axis represents the percentage of the fabric's warp breaking strength to its initial strength in the tensile test. In the figure, solid lines combined with circular markers, dashed lines combined with square markers, and dotted lines combined with triangular markers correspond to the retention rate decay trajectories of Examples 1, 2, and 3, respectively, while dotted lines combined with diamond markers represent the evolution state of Comparative Example 1 under the same conditions.

[0124] The test results are as follows:

[0125] Based on the data in Table 4 and Figure 4 It is evident that the grafting strategy employing alkali swelling combined with epoxy ring-opening addition can impart antibacterial activity to the fibers while maintaining the original load-bearing capacity of the base fabric. Medical personnel face frequent fabric washing and disinfection in their daily work, and the structural mechanical stability of the fabric determines the service life of protective clothing. In Examples 1 to 3, the initial strength distribution of the unwashed fabrics ranged from 471.2 N to 496.5 N. After 10 cycles of high-concentration chlorine washing, the warp breaking strength retention rate remained at a relatively high level of 81.2% to 88.9%.

[0126] The low-concentration sodium hydroxide used in the preparation process only breaks the hydrogen bonds between cellulose macromolecules, resulting in controlled and limited swelling without inducing depolymerization of the macromolecular chains. The subsequent etherification reaction occurs on the primary hydroxyl side chains of cellulose; this covalent modification avoids direct damage to the cellulose pyran ring skeleton. The generated ether bonds exhibit chemical inertness in slightly acidic or slightly alkaline sodium hypochlorite washing solutions, allowing the load-bearing yarn to maintain structural continuity even after repeated oxidative washing.

[0127] The mechanical degradation curves shown in Comparative Example 1 confirm the structural defects inherent in the traditional oxidative modification pathway. The initial strength of Comparative Example 1 was only 391.4 N, but after 10 washes, the load-bearing capacity plummeted to 186.2 N, and the strength retention rate dropped to 47.5%. The oxidation system catalyzed by 2,2,6,6-tetramethylpiperidine oxide triggered deep degradation of the cellulose molecular chains.

[0128] During oxidation, the hydroxyl group at the C6 position is converted into a carboxyl or aldehyde group, and the accompanying β-elimination reaction breaks the originally continuous β-1,4-glycosidic bond. The short-chain cellulose, deprived of its degree of polymerization support, is subjected to the dual erosion of strong sodium hypochlorite oxidation and mechanical abrasion in the subsequent chlorine-containing washing environment, leading to the disintegration and collapse of the microfibrillated structure within the yarn. Based on various strength evolution data, this solution, relying on a non-destructive etherification grafting method, blocks the oxidative degradation pathway of cellulose macromolecules during functionalization, ensuring the high-density loading of active components while guaranteeing the tensile strength requirements of medical garment fabrics against repeated strong chlorine washing.

[0129] Test Example 5: Comparative Test of Long-Lasting Antibacterial and Antiviral Efficacy Decrease After Multiple Chlorination Washes

[0130] Fabric samples from Examples 1, 2, 3, and Comparative Example 1 that underwent 0, 5, and 10 standard chlorine washing cycles (with an effective chlorine concentration of 500 mg / L and a pH adjusted to 6.0) and were dried were cut into square fabric scraps with a side length of 5 mm for later use.

[0131] Following the shaking method in GB / T 20944.3 Standard for Evaluation of Antimicrobial Properties of Textiles, accurately weigh 0.75g of the fabric scraps from each stage and place them in separate 250mL Erlenmeyer flasks. Add 50mL of a 1×10⁻⁶ solution to each flask. 5 The test culture of Staphylococcus aureus (ATCC 6538) at CFU / mL was prepared by fixing the Erlenmeyer flask in a constant temperature shaking incubator and shaking continuously at 150 r / min for 24 h at 37 °C.

[0132] After shaking, the mixed bacterial solution in each flask was taken out and serially diluted. The diluted solution was evenly spread on the surface of nutrient agar medium plates and incubated upside down in a 37℃ incubator for 24 hours. The number of live colonies generated on each plate was counted by colony counter and compared with the data of the blank control group without fabric samples. The antibacterial rate (%) of the fabric at different washing stages was calculated.

[0133] According to the ISO 18184 standard for the determination of antiviral activity of textiles, a suspension of Phi6 bacteriophage (an enveloped RNA virus that specifically infects Pseudomonas and is used as a substitute test for enveloped viruses such as coronaviruses) was inoculated onto the surface of a 2cm×2cm fabric sample that had been treated with chlorine and kept at 25°C for 2 hours for contact reaction.

[0134] Add 20 mL of eluent containing a neutralizing agent to the inoculated fabric sample, and use a vortex mixer to fully wash away the virus particles attached to the fiber surface. Use the double-layer agar plate method to count the surviving phages in the eluent, and calculate the antiviral rate (%) of the fabric at each washing stage in combination with the control group data.

[0135] Table 5. Test data on the long-term biological protective efficacy of fabrics in Examples 1 to 3 and Comparative Example 1

[0136] Sample Name Antibacterial rate after 0 washes (%) Antibacterial rate after 5 washes (%) Antibacterial rate after 10 washes (%) Antiviral rate after 0 washes (%) Antiviral rate after 5 washes (%) Antiviral rate after 10 washes (%) Example 1 99.8 98.4 95.7 99.1 96.2 92.8 Example 2 99.5 96.1 93.4 98.6 94.7 90.5 Example 3 98.7 95.2 91.8 97.4 92.1 88.6 Comparative Example 1 98.2 64.7 31.5 96.8 51.3 24.2

[0137] Figure 5 The horizontal axis represents the number of washing cycles using standard sodium hypochlorite solution, and the vertical axis represents the kill / inhibition ratio of the fabric against Staphylococcus aureus. Solid lines with circular markers, dashed lines with square markers, and dotted lines with triangular markers depict the retention trends of antibacterial properties in Examples 1, 2, and 3, respectively, while dotted lines with diamond markers reveal the decay trajectory of the antibacterial rate in Comparative Example 1.

[0138] The test results are as follows:

[0139] Based on the data in Table 5 and Figure 5 It is known that grafting haloamine precursors onto the fiber backbone through stable chemical bonds and synergistically loading metal nanoclusters can block the damage to the bioprotective efficacy of fabrics caused by the washing and disinfection environment. Medical textiles are frequently exposed to washing media rich in moisture and oxidants during their clinical service life; the chemical resistance of the protective coating interface is crucial to the safety of infection control. Examples 1 to 3 maintained antibacterial and antiviral rates above 97.4% without washing. After 10 washing cycles containing sodium hypochlorite, the decline in these two key indicators was limited, with the test values ​​for Example 1 stabilizing at 95.7% and 92.8%. The covalent etherification reaction endowed the functional groups with a stable structure resistant to hydrolysis.

[0140] The ether bonds formed on the side chains of cellulose can remain closed during mechanical rubbing and alternating acid-base water baths, allowing the amino acid-modified halogen amine precursor to remain on the fabric surface. This ensures that each chlorine washing operation can successfully convert NH bonds into N-Cl bonds with strong oxidizing and bactericidal capabilities.

[0141] The co-deposited zinc-doped copper oxide nanocrystals further released localized metal ions and reactive oxygen species, which punctured and destroyed the bacterial cell membrane structure and the outer protein envelope of the bacteriophage. This synergistic protection mechanism remained intact after being washed with water.

[0142] The traditional esterification grafting technology used in Comparative Example 1 revealed inherent defects in the water-based washing system. Comparative Example 1 exhibited an antibacterial rate of 98.2% in the initial state, which decreased to 64.7% after 5 washes, and dropped to 31.5% at the 10th wash point. The antiviral index showed the same downward trend.

[0143] The ester bonds introduced by TEMPO oxidation are inherently hydrophilic and unstable. Free hydroxide ions and water molecules in weakly acidic or weakly alkaline detergents directly attack the carbon-oxygen double bonds of the ester groups, inducing bond breaking.

[0144] Functional molecules with antibacterial and antiviral activities lose their anchoring points on cotton fibers and are detached and lost from the fabric surface with the flow of water. Once the graft carrier is detached, subsequent soaking with sodium hypochlorite cannot restore the original N-Cl centers.

[0145] By combining the evolutionary differences of each group of data, the ether bond network constructed in this scheme effectively anchors the bio-killing module, solving the technical problem of accelerated dissipation of protective function of medical and nursing textiles after repeated disinfection.

[0146] Test Example 6:

[0147] Using a utility knife, the fabric samples from Examples 1, 2, 3, and Comparative Example 2 that had completed the final cross-linking and curing step but had not been activated with sodium hypochlorite were uniformly cut into standard test blocks of 15cm × 15cm. To prevent yarn from falling off during the washing process, the edges of all test blocks were overlocked and sewn together.

[0148] Each group of sewn fabric test blocks was placed into the washing drum of a standard industrial washing tester. 2 g / L of AATCC standard reference detergent was added. The continuous washing program was started under the conditions of a water level ratio of 1:30 and a water temperature of 40°C. The equipment was paused after completing 1, 3 and 5 standard washing cycles, respectively. The corresponding batch of fabric samples was retrieved and dried at 80°C using a flat-width setting machine.

[0149] Fabrics treated with different washing cycles were laid flat on a test platform. Using a portable spectrophotometer, five test points were randomly selected on the back of each fabric sample in the color-developing coating area, and L values ​​were read. * a * and b * The numerical values ​​serve as the background color data before contact with the disinfectant at the corresponding stage.

[0150] Using a microsyringe, draw 0.5 mL of sodium hypochlorite standard test solution with an effective chlorine concentration of 500 mg / L and add it dropwise at a uniform rate to the fabric coating area. Let it stand for 30 seconds to ensure that the droplet fully penetrates and completes the oxidation and color development reaction.

[0151] The colorimeter probe was aimed again at the area covered by the discolored droplet to collect the colorimetric values ​​after the reaction. Combined with the background colorimetric data at the same stage, the total color difference of each sample after different washing cycles was calculated using the CIE1976 color difference formula to evaluate the water washing resistance of the colorimetric coating.

[0152] Table 6. Color development and color difference test data of fabrics from Examples 1 to 3 and Comparative Example 2 after industrial washing.

[0153] Sample Name Total color difference after 0 washes Total color difference after one wash Total color difference after 3 washes Total color difference after 5 washes Example 1 49.2 47.8 44.5 41.2 Example 2 56.6 55.1 52.3 48.7 Example 3 44.1 42.6 39.8 37.1 Comparative Example 2 45.8 21.3 8.4 2.1

[0154] Figure 6 The horizontal axis represents the number of industrial washing cycles containing the standard reference detergent, and the vertical axis represents the color difference caused by the fabric coming into contact with the chlorine-containing standard solution after washing. In the figure, solid lines combined with circular markers, dashed lines combined with square markers, and dotted lines combined with triangle markers correspond to the numerical trends of Examples 1, 2, and 3, respectively, while dotted lines combined with diamond markers represent the evolution of Comparative Example 2 under the same washing conditions.

[0155] The test results are as follows:

[0156] Based on the data in Table 6 and Figure 6 It is evident that introducing a water-based polyurethane crosslinking network into the color-developing coating is a prerequisite for ensuring the practical durability of the intelligent monitoring function. Medical garments inevitably undergo frequent washing and decontamination processes during their actual operational cycle; the ability of the functional microparticles coated on the surface to resist water flow impact and fabric friction directly determines the service life of the sensing mechanism.

[0157] Examples 1 to 3 exhibited initial color difference values ​​ranging from 44.1 to 56.6 in the unwashed state. After completing 5 standard water washing cycles, the test areas still showed clear color transformation when exposed to chlorine-containing solutions, with the color difference of each sample remaining in the range of 37.1 to 48.7. This functional retention is attributed to the encapsulation effect of the fixing agent component in the coating system after film formation.

[0158] Waterborne polyurethane molecular chains undergo dehydration condensation in a baking thermal field at 150℃, interweaving on the back of a pure cotton base fabric to form a flexible mesh film. Polylactic acid microspheres are firmly anchored in the fiber gaps by a three-dimensional polymer network. The film-forming barrier of polyurethane prevents the washing liquid from directly peeling off the microspheres, while its unique porous and breathable structure allows water molecules and hypochlorite ions to easily penetrate into the coating and reach the color development core during detection.

[0159] The coating system lacking network support exhibited significant fragility in the face of mechanical forces. Observation of the data evolution process in Comparative Example 2 provides reverse confirmation. The unwashed fabric of Comparative Example 2 did indeed possess a color difference response of 45.8, but after a single wash, the test value dropped to 21.3, and after 5 washes, it remained at only 2.1. At this point, the fabric surface no longer showed any visible color change upon contact with disinfectant. Comparative Example 2 excluded water-based polyurethane fixing agents when preparing the color-developing coating solution, relying solely on the weak adhesion generated by the evaporation of moisture from the microspheres themselves to remain on the fabric surface.

[0160] The impeller shearing force generated in industrial washing machines, the mutual scraping between fabrics, and the wetting and penetration of surfactants disrupt this unstable surface adhesion. Polylactic acid microspheres encapsulating the color developer are massively detached and lost under the influence of the washing water flow, causing the fabric to completely lose its visual responsiveness to hypochlorous acid. Comparing the slippage patterns of various test indicators, the composite coating system constructed with the participation of film-forming substances compensates for the insufficient resistance to washing loss in simple microparticle coatings, providing an engineered solution for the long-term application of intelligent color development technology in medical and protective fabrics.

[0161] Test Example 7:

[0162] According to the ISO 10993-12 standard, 2.0g of unactivated antibacterial and antiviral pure cotton fabric samples prepared in Examples 1, 2, 3 and Comparative Example 3 were weighed respectively. After sterilization by double-sided ultraviolet irradiation, they were immersed in sterile centrifuge tubes containing 20mL of MEM medium containing 10% fetal bovine serum. The samples were continuously shaken and extracted in a constant temperature shaker at 37℃ at a speed of 120r / min for 24h. The supernatant in the centrifuge tubes was collected as the original test extract with a concentration of 100%.

[0163] L929 mouse fibroblasts in the logarithmic growth phase were digested with trypsin and resuspended by centrifugation, and the cell suspension concentration was adjusted to 1×10⁻⁶. 4 Cells were seeded at a rate of 100 μL per well using a multichannel pipette into 96-well cell culture plates and incubated for 24 hours in a cell culture incubator containing 5% carbon dioxide and maintained at 37°C until the cells were fully adhered and grown.

[0164] The original culture medium in the 96-well plate was aspirated, and the collected extracts of each sample were added to the corresponding test wells. Wells with only fresh MEM culture medium were set as negative control groups, and wells with culture medium containing 0.64% phenol were set as positive control groups. The culture plates were put back into the incubator for co-incubation, and three observation time nodes were set at 24h, 48h and 72h respectively.

[0165] After reaching the preset culture time point, add 10 μL of 5 mg / mL MTT working solution to each test well, and put it back into the incubator to incubate in the dark for 4 h to promote the reduction of MTT substrate to blue-purple formazan crystals by succinate dehydrogenase in the mitochondria of surviving cells.

[0166] Use a pipette to aspirate the liquid from the wells, add 150 μL of dimethyl sulfoxide to each well, place the 96-well plate on a micro-shaker and shake at low speed for 10 min to dissolve the crystals formed, and use an ELISA reader to read the absorbance value of each well at a wavelength of 490 nm. Divide the absorbance of each experimental group by the absorbance of the negative control group to calculate the relative cell proliferation rate (%).

[0167] Table 7. Data on relative cell proliferation rate of fabric extracts from Examples 1 to 3 and Comparative Example 3

[0168] Sample Name 24-hour relative proliferation rate (%) Relative proliferation rate at 48h (%) Relative proliferation rate (%) at 72h Example 1 96.4 94.2 92.8 Example 2 98.1 95.7 94.3 Example 3 97.5 96.2 93.9 Comparative Example 3 84.3 76.5 68.2

[0169] Figure 7 The horizontal axis represents the duration of co-culture of mouse fibroblasts with the culture medium containing the fabric extract, and the vertical axis represents the percentage of surviving cells proliferating as calculated by absorbance. Solid lines with circular markers, dashed lines with square markers, and dotted lines with triangular markers record the changes in cell activity in Examples 1, 2, and 3, respectively, while dotted lines with diamond markers reveal the cytotoxic response of Comparative Example 3 within the same experimental period.

[0170] The test results are as follows:

[0171] Based on the data in Table 7 and Figure 7 It is evident that introducing amino acid modification is a necessary means to eliminate potential cytotoxicity on the fabric surface. Medical protective clothing fabrics inevitably come into continuous contact with the sweat and sebum of the human body during actual wear; the biocompatibility of residual chemicals on the surface determines whether textiles can be safely used in medical settings.

[0172] The fabric extracts from Examples 1 to 3, when co-cultured with L929 mouse fibroblasts for 24 hours, showed a relative proliferation rate ranging from 96.4% to 98.1%. Even after extending the culture time to 72 hours, this value remained within the safety range of 92.8% to 94.3%. This data reflects the purifying effect of the post-treatment process on the reaction interface. During the halogen precursor grafting stage, some of the epoxy intermediates converted from 3-(3-chloro-2-hydroxypropyl)-5,5-dimethylhydantoin were limited by steric hindrance and failed to undergo ring-opening binding with the hydroxyl groups on the cellulose backbone.

[0173] The addition of L-lysine provides amino side chains containing active protons, which specifically capture residual epoxy groups hanging on the fabric surface. Consuming the reactive epoxy structure interrupts the pathway for non-specific cross-linking with human skin cell membrane proteins, thus preventing irritant dermatitis or cellular metabolic stagnation at the contact site.

[0174] Modified fabrics without amino acid end-capping exposed the toxicological risks of the underlying synthetic pathway. Comparative Example 3, which omitted the L-lysine addition step, showed a decrease in relative cell proliferation rate to 84.3% at the 24-hour test node. As the extracted substances accumulated in the culture medium and the reaction time was prolonged, the relative proliferation rate further declined to 68.2% at 72 hours. The unopened epoxy groups in their free state exhibit strong electrophilic properties, easily detaching from the fiber surface in aqueous media and entering surrounding biological tissues, interfering with the normal metabolic cycle of fibroblasts and causing a continuous decline in the test indicators.

[0175] In textile chemical modification research, there is often a design conflict between functional enhancement and safety assurance. Choosing bio-derived amino acids as reaction quenchers balances this technical contradiction. By combining cell activity data from different test groups at different time points, a chemical end-capping strategy targeting residual groups eliminates the associated toxicological risks of covalent grafting, establishing a safety baseline for antibacterial fabrics intended for direct human contact.

Claims

1. A reusable, washable, antibacterial, and cotton-resistant fabric for medical gowns, characterized in that, The invention includes pure cotton fabrics grafted with amino acid-modified haloamine precursors or their activated forms, and loaded with zinc-doped copper oxide nanoclusters. The amino acid-modified haloamine precursor is formed by a stepwise grafting reaction of 3-(3-chloro-2-hydroxypropyl)-5,5-dimethylhydantoin with L-lysine. The pure cotton fabric is coated with a color-developing coating on one side of its back side, and the color-developing coating is cross-linked and cured by baking at 145-155°C for 2-4 minutes. The color-developing coating contains polylactic acid microspheres encapsulating 3,3′,5,5′-tetramethylbenzidine and an aqueous polyurethane fixing agent.

2. The reusable, washable, antibacterial, and cotton-resistant fabric according to claim 1, characterized in that, The pure cotton fabric is a 40-60 count pure cotton fabric, and the weight per square meter of the pure cotton fabric is 110-130 g / m². 2 .

3. The reusable, washable, antibacterial, and cotton-resistant fabric according to claim 1, characterized in that, The zinc-doped copper oxide nanoclusters are generated by in-situ coordination precipitation of a mixed salt solution containing zinc nitrate and copper nitrate, wherein the molar fraction of zinc ions in the mixed salt solution is 0.05 to 0.

15.

4. The reusable, washable, antibacterial, and cotton-resistant fabric according to claim 1, characterized in that, The mass ratio of the polylactic acid microspheres to the waterborne polyurethane fixing agent is 1:2 to 1:

4.

5. A method for preparing a reusable, washable, antibacterial, and cotton-resistant fabric for medical protective clothing, characterized in that, The preparation of the reusable, chlorine-washable, antibacterial, and cotton-resistant fabric according to any one of claims 1-4 includes the following steps: The pure cotton fabric is immersed in a sodium hydroxide solution for alkaline treatment, and then the pure cotton fabric is taken out and washed with water until neutral to obtain activated pure cotton fabric. The activated pure cotton fabric was immersed in a mixed alkaline solution containing 3-(3-chloro-2-hydroxypropyl)-5,5-dimethylhydantoin, sodium carbonate and sodium hydroxide for reaction. Then, L-lysine was added to the mixed alkaline solution to continue the reaction, completing the stepwise grafting reaction. The activated pure cotton fabric after the reaction was washed with water and neutralized with acetic acid, and then dried to obtain pure cotton fabric grafted with amino acid modified haloamine precursor. The amino acid-modified haloamine precursor grafted pure cotton fabric was immersed in a mixed salt solution containing zinc nitrate and copper nitrate for water squeezing treatment, and then immersed in sodium hydroxide solution for in-situ coordination precipitation. After washing and drying, antibacterial and antiviral pure cotton fabric loaded with zinc-doped copper oxide nanoclusters was obtained. Polylactic acid microspheres embedded with 3,3′,5,5′-tetramethylbenzidine were mixed with an aqueous polyurethane fixing agent to prepare a color developing coating liquid. The color developing coating liquid was applied to the back of the antibacterial and antiviral pure cotton fabric loaded with zinc-doped copper oxide nanoclusters, and then baked to crosslink and cure, resulting in an unactivated antibacterial and antiviral pure cotton fabric. The unactivated antibacterial and antiviral pure cotton fabric was immersed in sodium hypochlorite standard solution for washing and activation reaction. After rinsing until there was no chlorine odor and drying, a multi-chlorine washable antibacterial cotton fabric for medical clothing was obtained in the activated form of grafted halogenated amine precursor.

6. The preparation method according to claim 5, characterized in that, The concentration of the sodium hydroxide solution is 0.3–0.5 mol / L; The alkali treatment temperature is 45–55°C, and the treatment time is 20–30 min.

7. The preparation method according to claim 5, characterized in that, The concentrations of each component in the mixed alkaline solution are: 3-(3-chloro-2-hydroxypropyl)-5,5-dimethylhydantoin: 0.08–0.15 mol / L; Sodium carbonate: 0.08–0.12 mol / L; Sodium hydroxide: 0.04–0.06 mol / L; The pH of the mixed alkaline solution is controlled at 9.0–10.5, and the reaction is carried out at 45–55°C for 2.0–3.0 h.

8. The preparation method according to claim 5, characterized in that, The concentration of added L-lysine is 0.01–0.02 mol / L, and the reaction continues for 25–35 min. The specific procedure for neutralization using acetic acid is as follows: Neutralize to pH 6.0–7.0 with acetic acid at a concentration of 0.03–0.08 mol / L.

9. The preparation method according to claim 5, characterized in that, The total concentration of the mixed salt solution is 0.04–0.06 mol / L, the water-squeezing treatment maintains a water-squeezing rate of 60–80%, and the concentration of the sodium hydroxide solution used for in-situ coordination precipitation is 0.04–0.06 mol / L.

10. The preparation method according to claim 5, characterized in that, The effective chlorine concentration of the sodium hypochlorite standard solution is 400–600 mg / L, and the pH of the sodium hypochlorite standard solution is 5.5–6.

5. The activation reaction takes 20–40 minutes.

Images