Antibacterial finishing agent as well as preparation method and application thereof

Abstract

The invention provides an antibacterial finishing agent and a preparation method and application thereof, and belongs to the technical field of textile assistants, the antibacterial finishing agent comprises the following raw materials: a chitosan-phytic acid-gallic acid graft copolymer, a citric acid-chitosan oligosaccharide cross-linking agent, sodium polyglutamate, a natural surfactant and water. During application, a padding-baking process is adopted, the finishing agent is diluted into 5-20 g / L working solution, the pH is 6-6.5, two times of padding and two times of rolling are performed, pre-drying is performed for 2-3 min at the temperature of 90-100 DEG C, baking is performed for 2-3 min at the temperature of 150-160 DEG C, an antibacterial layer which is resistant to washing more than or equal to 50 times and has the antibacterial rate more than or equal to 90% can be formed on pure cotton, pure hemp, pure silk and blended fabric thereof, and the finished fabric is soft in hand feeling, free of metal residues and biodegradable.

Description

Technical Field

[0001] This invention relates to the field of textile auxiliaries technology, specifically to an antibacterial finishing agent, its preparation method, and its application. Background Technology

[0002] With the rise of the global economy and the frequent occurrence of public health emergencies, textiles have been expected to have a "second skin." Antibacterial properties are no longer exclusive to special scenarios such as medical care and military / police use, but have rapidly permeated almost every sub-sector, including everyday clothing, baby products, hotel linens, automotive interiors, rail transit seats, sportswear, medical dressings, pet supplies, and even air filtration materials. However, antibacterial finishing agents that simultaneously achieve excellent performance across the five dimensions of "high efficiency, safety, durability, environmental friendliness, and low cost" have long been lacking, becoming a prominent bottleneck restricting industrial upgrading.

[0003] Firstly, while inorganic metal-based antibacterial agents, represented by nano-silver, nano-copper, and nano-zinc oxide, possess advantages such as broad spectrum, high efficiency, and heat resistance, their effectiveness essentially relies on the continuous dissolution of metal ions to disrupt the microbial membrane potential or interfere with enzyme systems. This "dissolution-based" bactericidal mechanism, while providing highly effective antibacterial action, also raises three major concerns: First, metal ions are easily complexed and lost by sweat, sebum, or detergents, resulting in insufficient antibacterial durability; second, free metal ions can penetrate the human body through the skin, and long-term exposure may disrupt the balance of trace elements, inducing allergies or cytotoxicity; third, metal ions accumulated in laundry wastewater have irreversible ecotoxicity to aquatic organisms, and many European and American countries have listed them as key monitored pollutants, with exported textiles facing stringent restrictions such as REACH and OEKO-TEX 2025 regulations.

[0004] Secondly, cationic organic antibacterial agents such as quaternary ammonium salts, polyhexamethylene biguanide hydrochloride (PHMB), and halogenated amine compounds primarily kill bacteria through contact, are relatively inexpensive, and have high reactivity, but their wash resistance is generally insufficient. This is because the electrostatic bond between their cationic groups and the negative charge on the fiber is easily replaced by anionic surfactants. After 5-10 washes with conventional household detergents, the antibacterial rate decreases by more than 50%. Increasing the crosslinking density can lead to side effects such as a stiff hand feel, decreased breathability, and yellowing. In addition, some low-molecular-weight quaternary ammonium salts pose potential risks of cytotoxicity and bioaccumulation, and the EU's BPR regulations have set stricter thresholds for their concentration in intimate apparel textiles.

[0005] Third, although organosilicon quaternary ammonium salts or their composite systems with polyurethane and polysiloxane can form flexible films on the fiber surface and improve the feel of fabrics, their long-chain siloxane skeletons have limited penetration depth into the microporous structures of natural fibers such as cotton, linen, and silk, often resulting in an antibacterial blind zone of "surface film formation, core blank"; and high-temperature baking (160-180℃) can easily cause fabric yellowing, especially affecting light-colored or bleached fabrics significantly; at the same time, some silane coupling agents release methanol or ethylene glycol ethers after hydrolysis, posing a risk of VOC emissions.

[0006] Fourth, while natural antibacterial agents such as chitosan, tea polyphenols, grape seed extract, berberine, catechins, and plant essential oils have advantages such as renewability, good biocompatibility, and biodegradability, their antibacterial active groups (phenolic hydroxyl groups, amino groups, and double bonds) are easily oxidized and deactivated under light, high temperature, and alkaline washing conditions. Furthermore, their small molecular weight and lack of effective cross-linking sites result in low binding strength to fibers, leading to insufficient antibacterial durability. Currently, the industry commonly improves stability through microencapsulation, cyclodextrin inclusion, and metal ion complexation, but this brings new problems such as complex processes, soaring costs, and a stiff feel.

[0007] With the explosive growth of high-end applications such as infant textiles, medical dressings, and automotive interiors, single antibacterial functions are no longer sufficient to meet the demand. The market urgently needs "one-bath multi-effect" finishing agents that combine antibacterial, antiviral, anti-mite, deodorizing, self-cleaning, flame retardant, UV protection, and moisturizing properties. However, existing technologies often achieve this through simple physical compounding of multiple auxiliaries, which easily leads to problems such as poor compatibility, precipitation and stratification, deterioration of hand feel, and decreased color fastness. In summary, developing a novel antibacterial finishing agent with a natural polymer backbone, introducing multiple antibacterial groups through mild chemical modification, and achieving covalent bonding of fibers with a biodegradable crosslinking agent, while simultaneously meeting comprehensive indicators such as "broad-spectrum high efficiency, water resistance of more than 50 washes, metal-free, formaldehyde-free, and biodegradable," has become a core technical challenge that urgently needs to be overcome in the field of textile auxiliaries, and is also a key path to promote the green upgrading of the global textile industry. Summary of the Invention

[0008] The purpose of this invention is to provide an antibacterial finishing agent, its preparation method and application. This finishing agent has high antibacterial activity, is water-resistant, leaves no metal residue, and is biodegradable.

[0009] The technical solution of this invention is implemented as follows:

[0010] This invention provides an antibacterial finishing agent, composed of the following raw materials by weight percentage:

[0011] Chitosan-phytic acid-gallic acid graft copolymer 15%-25%, citric acid-chitosan oligosaccharide crosslinking agent 1%-3%, sodium polyglutamate 0.5%-2%, natural surfactant 0.1%-0.5%, balance water.

[0012] As a further improvement of the present invention, the chitosan-phytic acid-gallic acid graft copolymer is prepared by the following method:

[0013] S1. Dissolve chitosan in 1 wt% acetic acid solution, add 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide, and adjust the pH of the system to 5.5-6 with a pH adjuster;

[0014] S2. Dissolve phytic acid in water to prepare an aqueous solution of 50 wt% based on phytic acid. Adjust the pH to 6-6.5 with NaOH and then add it dropwise to the above chitosan solution within 10 min. Stir and react at 50-60℃ for 1-2 h.

[0015] S3. Dissolve gallic acid in water to prepare a 5-10 wt% aqueous solution, adjust the pH to 6.5-7 with NaOH, and add it dropwise to the reaction solution in step S2 within 10 min. Stir the reaction at 50-60℃ for 1-2 h, add ethanol to precipitate the product, filter, wash with ethanol and dry under vacuum at 50-60℃ to obtain chitosan-phytic acid-gallic acid graft copolymer powder.

[0016] As a further improvement of the present invention, the chitosan has a molecular weight of 50,000-200,000 Da and a degree of deacetylation ≥85%.

[0017] As a further improvement of the present invention, the pH adjuster in step S1 is either NaOH or hydrochloric acid; the mass ratio of chitosan to acetic acid solution is (2-3):100; the mass ratio of chitosan, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and N-hydroxysuccinimide is 1:(0.9-1):(0.5-0.6).

[0018] As a further improvement of the present invention, the mass ratio of chitosan, phytic acid and gallic acid is 1:(0.5-0.6):(0.3-0.4).

[0019] As a further improvement of the present invention, the citric acid-chitosan oligosaccharide crosslinking agent is prepared by the following method:

[0020] S4. Add chitosan oligosaccharide, citric acid, and sodium hypophosphite to the reactor, mix, add deionized water, and stir at 100-200 rpm for 3-5 minutes to form a uniform wet slurry;

[0021] S5. Heat the reactor to 90-95℃, evacuate to -0.07~-0.08MPa, and dehydrate for 20-30min; continue heating to 110-115℃, maintain the vacuum at -0.08~-0.09MPa, and melt for 20-30min.

[0022] S6. Cool, discharge, crush, and pass through a 200-mesh sieve to obtain citric acid-chitosan oligosaccharide crosslinking agent powder with a moisture content ≤3%.

[0023] As a further improvement of the present invention, the degree of deacetylation of the chitosan oligosaccharide in step S4 is ≥85%, and the molecular weight is 1kDa-2kDa; the mass ratio of chitosan oligosaccharide, citric acid, and sodium hypophosphite is 1:(0.8-1.2):(0.02-0.03); and the mass of deionized water added is 15%-20% of the total mass of chitosan oligosaccharide and citric acid.

[0024] As a further improvement of the present invention, the natural surfactant is selected from at least one of saponins and sophorolipids, and the sodium polyglutamate has a molecular weight of 50-300 kDa.

[0025] This invention further protects a method for preparing the above-mentioned antibacterial finishing agent, comprising the following steps:

[0026] According to the formula, chitosan-phytic acid-gallic acid graft copolymer, citric acid-chitosan oligosaccharide crosslinking agent, sodium polyglutamate, natural surfactant and water are mixed evenly, the pH is adjusted to 6-6.5, and the mixture is stirred at 70-80℃ and 200-300rpm for 1-2 hours. After cooling to room temperature, an antibacterial finishing agent is obtained.

[0027] This invention further protects the application of the above-mentioned antibacterial finishing agent in textiles, and uses a pad-drying process to finish the textiles, including the following steps:

[0028] a) Preparation of working solution: Dilute the antibacterial finishing agent with deionized water to 5-20 g / L, and adjust the pH to 6.0-6.5 with 0.1 mol / L NaOH or 0.1 mol / L HCl;

[0029] b) Padding: The textile is immersed in the working solution at a bath ratio of 1:10-1:20, and then padding is performed twice. The roller pressure is 0.05-0.10 MPa, and the liquid carry-over rate is controlled at 70-100%.

[0030] c) Pre-drying: Pre-dry with hot air at 90-100℃ for 2-3 minutes;

[0031] d) Baking: Baking at 150-160℃ for 2-3 minutes;

[0032] e) Post-treatment: Cool at room temperature, wash with water, and dry to obtain antibacterial textiles with a wash resistance of ≥50 times and an antibacterial rate of ≥90%.

[0033] The textiles are made of pure cotton, pure linen, pure silk, or blends thereof in any proportion.

[0034] The principles and beneficial effects of this invention are as follows:

[0035] 1. In the chitosan-phytic acid-gallic acid graft copolymer, the chitosan backbone is positively charged under weakly acidic conditions. It can bind to the negative charge of the bacterial cell wall through electrostatic attraction, thereby disrupting the membrane integrity. The phosphate groups at the end of the phytic acid can chelate with calcium / magnesium ions in the bacterial membrane phospholipids, blocking membrane repair and achieving "membrane destruction" sterilization. The phenolic hydroxyl groups introduced by gallic acid continuously release reactive oxygen species (ROS) in a slightly acidic environment, attacking the bacterial nucleic acid and enzyme systems. The covalent grafting structure of the three components avoids the loss of free monomers and ensures that the antibacterial rate is maintained at ≥90% after 50 water washes.

[0036] 2. When citric acid is baked at high temperature, it forms hydrolyzable ester bonds with chitosan oligosaccharides and establishes "flexible bridges" between cellulose hydroxyl groups, so that antibacterial molecules are firmly anchored to the fiber; the low cross-linking density ensures that the fabric is soft and breathable, and there is no formaldehyde residue after high-temperature decomposition.

[0037] 3. Sodium polyglutamate plays a triple role in finishing agents: fiber affinity, solubilization, and moisturizing. First, its sodium γ-carboxylate groups can form hydrogen bonds or weak ionic bonds with the hydroxyl groups on the surface of cellulose fibers such as cotton and linen, improving the uniform adsorption rate of the finishing agent on the fibers and reducing "white bloom" or "migration." Second, the polymer chains carry a large number of negative charges, which can electrostatically repel copolymer particles and prevent the concentrate from flocculating / precipitating during long-term storage or at low temperatures. Simultaneously, after absorbing moisture, it forms a soft hydrogel layer, reducing the stiffness of the fabric after baking and maintaining breathability.

[0038] 4. Biodegradable natural surfactants can reduce the surface tension of the working fluid, ensuring padding penetration; at the same time, as emulsifiers and dispersants, they prevent copolymer particles from agglomerating, leaving no residue and preventing yellowing after baking.

[0039] In summary, the positively charged chitosan-phytic acid "membrane disruption" + phenolic hydroxyl ROS "chemical killing" + citric acid-chitosan oligosaccharide "covalent anchoring" + sodium polyglutamate "feel optimization" + natural surfactant "uniform spreading" constitute an integrated antibacterial system that is "broad-spectrum, durable, green and soft". Detailed Implementation

[0040] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] Example 1

[0042] This embodiment provides an antibacterial finishing agent, which is composed of the following raw materials by weight percentage:

[0043] Chitosan-phytic acid-gallic acid graft copolymer 15%, citric acid-chitosan oligosaccharide crosslinking agent 1%, sodium polyglutamate 0.5%, natural surfactant 0.1%, balance water;

[0044] Among them, sodium polyglutamate has a molecular weight of 50kDa, and the natural surfactant is soybean saponin;

[0045] Chitosan-phytic acid-gallic acid graft copolymer is prepared by the following method:

[0046] S1. Dissolve 10g of chitosan (molecular weight of 50,000 Da, degree of deacetylation ≥ 85%) in 500g of 1wt% acetic acid solution, add 9g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 5g of N-hydroxysuccinimide, and adjust the pH of the system to 5.5 with a pH adjuster.

[0047] S2. Dissolve 5g of phytic acid in 5g of water to prepare an aqueous solution with a phytic acid content of 50wt%. Adjust the pH to 6.5 with NaOH and then add it dropwise to the above chitosan solution within 10 minutes. Stir and react at 60°C for 1 hour.

[0048] S3. Dissolve 3g of gallic acid in 57g of water to prepare a 5wt% aqueous solution, adjust the pH to 6.5 with NaOH, and add it dropwise to the reaction solution in step S2 within 10min. Stir the reaction at 60℃ for 1h, add ethanol to precipitate the product, filter, wash with ethanol and dry under vacuum at 50℃ to obtain chitosan-phytic acid-gallic acid graft copolymer powder.

[0049] The citric acid-chitosan oligosaccharide crosslinking agent is prepared by the following method:

[0050] S4. Add 10g of chitosan oligosaccharide (degree of deacetylation ≥85%, molecular weight 1kDa), 8g of citric acid, and 0.2g of sodium hypophosphite to the reactor, mix, add 2.7g of deionized water, stir at 200rpm for 3min to form a uniform wet slurry.

[0051] S5. Heat the reactor to 95℃, evacuate to -0.08MPa, and dehydrate for 20 minutes; continue heating to 115℃, maintain the vacuum at -0.08MPa, and melt for 30 minutes.

[0052] S6. Cool, discharge, crush, and pass through a 200-mesh sieve to obtain citric acid-chitosan oligosaccharide crosslinking agent powder with a moisture content ≤3%.

[0053] A method for preparing an antibacterial finishing agent includes the following steps:

[0054] According to the formula, chitosan-phytic acid-gallic acid graft copolymer, citric acid-chitosan oligosaccharide crosslinking agent, sodium polyglutamate, natural surfactant and water are mixed evenly, the pH is adjusted to 6.5, and the mixture is stirred at 70℃ and 200rpm for 2 hours. After cooling to room temperature, an antibacterial finishing agent is obtained.

[0055] Example 2

[0056] This embodiment provides an antibacterial finishing agent, which is composed of the following raw materials by weight percentage:

[0057] Chitosan-phytic acid-gallic acid graft copolymer 25%, citric acid-chitosan oligosaccharide crosslinking agent 3%, sodium polyglutamate 2%, natural surfactant 0.5%, balance water;

[0058] Among them, sodium polyglutamate has a molecular weight of 50kDa, and the natural surfactant is soybean saponin;

[0059] Chitosan-phytic acid-gallic acid graft copolymer is prepared by the following method:

[0060] S1. Dissolve 10g of chitosan (molecular weight of 50,000 Da, degree of deacetylation ≥ 85%) in 500g of 1wt% acetic acid solution, add 9g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 5g of N-hydroxysuccinimide, and adjust the pH of the system to 5.5 with a pH adjuster.

[0061] S2. Dissolve 5g of phytic acid in 5g of water to prepare an aqueous solution with a phytic acid content of 50wt%. Adjust the pH to 6.5 with NaOH and then add it dropwise to the above chitosan solution within 10 minutes. Stir and react at 60°C for 1 hour.

[0062] S3. Dissolve 3g of gallic acid in 57g of water to prepare a 5wt% aqueous solution, adjust the pH to 6.5 with NaOH, and add it dropwise to the reaction solution in step S2 within 10min. Stir the reaction at 60℃ for 1h, add ethanol to precipitate the product, filter, wash with ethanol and dry under vacuum at 50℃ to obtain chitosan-phytic acid-gallic acid graft copolymer powder.

[0063] The citric acid-chitosan oligosaccharide crosslinking agent is prepared by the following method:

[0064] S4. Add 10g of chitosan oligosaccharide (degree of deacetylation ≥85%, molecular weight 1kDa), 8g of citric acid, and 0.2g of sodium hypophosphite to the reactor, mix, add 2.7g of deionized water, stir at 200rpm for 3min to form a uniform wet slurry.

[0065] S5. Heat the reactor to 95℃, evacuate to -0.08MPa, and dehydrate for 20 minutes; continue heating to 115℃, maintain the vacuum at -0.08MPa, and melt for 30 minutes.

[0066] S6. Cool, discharge, crush, and pass through a 200-mesh sieve to obtain citric acid-chitosan oligosaccharide crosslinking agent powder with a moisture content ≤3%.

[0067] A method for preparing an antibacterial finishing agent includes the following steps:

[0068] According to the formula, chitosan-phytic acid-gallic acid graft copolymer, citric acid-chitosan oligosaccharide crosslinking agent, sodium polyglutamate, natural surfactant and water are mixed evenly, the pH is adjusted to 6.5, and the mixture is stirred at 70℃ and 200rpm for 2 hours. After cooling to room temperature, an antibacterial finishing agent is obtained.

[0069] Example 3

[0070] This embodiment provides an antibacterial finishing agent, which is composed of the following raw materials by weight percentage:

[0071] Chitosan-phytic acid-gallic acid graft copolymer 20%, citric acid-chitosan oligosaccharide crosslinking agent 2%, sodium polyglutamate 1%, natural surfactant 0.3%, balance water;

[0072] Among them, sodium polyglutamate has a molecular weight of 50kDa, and the natural surfactant is soybean saponin;

[0073] Chitosan-phytic acid-gallic acid graft copolymer is prepared by the following method:

[0074] S1. Dissolve 10g of chitosan (molecular weight of 50,000 Da, degree of deacetylation ≥ 85%) in 500g of 1wt% acetic acid solution, add 9g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 5g of N-hydroxysuccinimide, and adjust the pH of the system to 5.5 with a pH adjuster.

[0075] S2. Dissolve 5g of phytic acid in 5g of water to prepare an aqueous solution with a phytic acid content of 50wt%. Adjust the pH to 6.5 with NaOH and then add it dropwise to the above chitosan solution within 10 minutes. Stir and react at 60°C for 1 hour.

[0076] S3. Dissolve 3g of gallic acid in 57g of water to prepare a 5wt% aqueous solution, adjust the pH to 6.5 with NaOH, and add it dropwise to the reaction solution in step S2 within 10min. Stir the reaction at 60℃ for 1h, add ethanol to precipitate the product, filter, wash with ethanol and dry under vacuum at 50℃ to obtain chitosan-phytic acid-gallic acid graft copolymer powder.

[0077] The citric acid-chitosan oligosaccharide crosslinking agent is prepared by the following method:

[0078] S4. Add 10g of chitosan oligosaccharide (degree of deacetylation ≥85%, molecular weight 1kDa), 8g of citric acid, and 0.2g of sodium hypophosphite to the reactor, mix, add 2.7g of deionized water, stir at 200rpm for 3min to form a uniform wet slurry.

[0079] S5. Heat the reactor to 95℃, evacuate to -0.08MPa, and dehydrate for 20 minutes; continue heating to 115℃, maintain the vacuum at -0.08MPa, and melt for 30 minutes.

[0080] S6. Cool, discharge, crush, and pass through a 200-mesh sieve to obtain citric acid-chitosan oligosaccharide crosslinking agent powder with a moisture content ≤3%.

[0081] A method for preparing an antibacterial finishing agent includes the following steps:

[0082] According to the formula, chitosan-phytic acid-gallic acid graft copolymer, citric acid-chitosan oligosaccharide crosslinking agent, sodium polyglutamate, natural surfactant and water are mixed evenly, the pH is adjusted to 6.5, and the mixture is stirred at 70℃ and 200rpm for 2 hours. After cooling to room temperature, an antibacterial finishing agent is obtained.

[0083] Comparative Example 1

[0084] The only difference between this comparative example and Example 1 is that no citric acid-chitosan oligosaccharide crosslinking agent is added, as detailed below:

[0085] An antibacterial finishing agent, comprising the following raw materials by weight percentage:

[0086] The composition consists of 15% chitosan-phytic acid-gallic acid graft copolymer, 0.5% sodium polyglutamate, 0.1% natural surfactant, and the remainder is water.

[0087] Among them, sodium polyglutamate has a molecular weight of 50kDa, and the natural surfactant is soybean saponin;

[0088] Chitosan-phytic acid-gallic acid graft copolymer is prepared by the following method:

[0089] S1. Dissolve 10g of chitosan (molecular weight of 50,000 Da, degree of deacetylation ≥ 85%) in 500g of 1wt% acetic acid solution, add 9g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 5g of N-hydroxysuccinimide, and adjust the pH of the system to 5.5 with a pH adjuster.

[0090] S2. Dissolve 5g of phytic acid in 5g of water to prepare an aqueous solution with a phytic acid content of 50wt%. Adjust the pH to 6.5 with NaOH and then add it dropwise to the above chitosan solution within 10 minutes. Stir and react at 60°C for 1 hour.

[0091] S3. Dissolve 3g of gallic acid in 57g of water to prepare a 5wt% aqueous solution, adjust the pH to 6.5 with NaOH, and add it dropwise to the reaction solution in step S2 within 10min. Stir the reaction at 60℃ for 1h, add ethanol to precipitate the product, filter, wash with ethanol and dry under vacuum at 50℃ to obtain chitosan-phytic acid-gallic acid graft copolymer powder.

[0092] A method for preparing an antibacterial finishing agent includes the following steps:

[0093] According to the formula, chitosan-phytic acid-gallic acid graft copolymer, sodium polyglutamate, natural surfactant and water are mixed evenly, the pH is adjusted to 6.5, and the mixture is stirred at 70℃ and 200rpm for 2 hours. After cooling to room temperature, an antibacterial finishing agent is obtained.

[0094] Comparative Example 2

[0095] The only difference between this comparative example and Example 1 is that chitosan is used instead of the chitosan-phytic acid-gallic acid graft copolymer.

[0096] An antibacterial finishing agent, comprising the following raw materials by weight percentage:

[0097] Chitosan 15%, citric acid-chitosan oligosaccharide crosslinking agent 1%, sodium polyglutamate 0.5%, natural surfactant 0.1%, balance water;

[0098] Among them, chitosan has a molecular weight of 50,000 Da (degree of deacetylation ≥ 85%), sodium polyglutamate has a molecular weight of 50 kDa, and the natural surfactant is soybean saponin.

[0099] The citric acid-chitosan oligosaccharide crosslinking agent is prepared by the following method:

[0100] S1. Add 10g of chitosan oligosaccharide (degree of deacetylation ≥85%, molecular weight 1kDa), 8g of citric acid, and 0.2g of sodium hypophosphite to the reactor, mix, add 2.7g of deionized water, stir at 200rpm for 3min to form a uniform wet slurry.

[0101] S2. Heat the reactor to 95°C, evacuate to -0.08MPa, and dehydrate for 20 minutes; continue heating to 115°C, maintain the vacuum at -0.08MPa, and melt for 30 minutes.

[0102] S3. Cool, discharge, crush, and pass through a 200-mesh sieve to obtain citric acid-chitosan oligosaccharide crosslinking agent powder with a moisture content ≤3%.

[0103] A method for preparing an antibacterial finishing agent includes the following steps:

[0104] According to the formula, chitosan, citric acid-chitosan oligosaccharide crosslinking agent, sodium polyglutamate, natural surfactant and water are mixed evenly, the pH is adjusted to 6.5, and the mixture is stirred at 70℃ and 200rpm for 2 hours. After cooling to room temperature, an antibacterial finishing agent is obtained.

[0105] Comparative Example 3

[0106] The following is the specific preparation process for using 0.2% silver-based antibacterial agent (nano-Ag) as an antibacterial finishing agent:

[0107] Take 2g of commercially available 20nm nano silver dispersion (solid content 10wt%), add 98g of deionized water, and mix well to obtain 0.2% Ag finishing solution.

[0108] Performance testing:

[0109] The antibacterial finishing agent prepared according to this invention was diluted with deionized water to 5 g / L, and the pH was adjusted to 6.5 with 0.1 mol / L NaOH or 0.1 mol / L HCl. Pure cotton textiles were immersed in the finishing agent working solution at a bath ratio of 1:10, subjected to two dips and two nips, with a roller pressure of 0.10 MPa and a liquid carry-over rate of 70%. The textiles were pre-dried with hot air at 90°C for 3 min, then baked at 160°C for 2 min. After cooling at room temperature, the textiles were washed with water and dried to obtain the antibacterial finished cotton fabric. Performance tests were then conducted. The test results are shown in Table 1.

[0110] Test Example 1: Antibacterial Performance Test

[0111] The procedure was performed according to GB / T 20944.3-2008 "Evaluation of Antimicrobial Properties of Textiles - Part 3: Shaking Method". 0.75g of treated cotton fabric (3 parallel samples) was taken, and *Escherichia coli* ATCC 25922 and *Staphylococcus aureus* ATCC 6538 were used as test bacteria, with a bacterial suspension concentration of 1×10⁻⁶. 5 CFU·mL⁻¹, shaken at 37℃ for 18 h; then incubated on a film for 24 h for counting. The inhibition rate is calculated as the average of the two strains.

[0112] The treated cotton fabric was washed 50 times using a wash fastness tester, and then the antibacterial rate was measured again to evaluate the fabric's wash fastness.

[0113] Test Example 2: Stiffness Test

[0114] The test was conducted according to GB / T 18318.1-2009 "Textiles - Determination of bending properties of fabrics - Part 1: Inclined plane method". Five 20cm × 2.5cm warp samples were conditioned at 20℃ and 65%RH for 24 hours. They were then placed horizontally on the slide of a fabric stiffness tester, with one end aligned with the baseline. The tester was advanced at a constant speed of 1cm / s until the free end touched the 41.5° inclined plane. The instrument reading was taken as the stiffness. The average value of the five samples was taken. A result ≤1.5cm was rated as "excellent".

[0115] Test Example 3: Biodegradability Test

[0116] According to ASTM D5511-18, 2g of sample was cut into pieces and placed together with inoculated sludge in an anaerobic bottle at 58℃. After 180 days, the CO2 / CH4 release was measured and the mass loss was calculated. ≥80% was considered biodegradable.

[0117] Test Example 4: Metal Residue Test

[0118] 0.2g of the fabric was digested by microwave HNO3-H2O2 and then analyzed by ICP-MS. 107 Ag、 63 Cu、 66 Zn, detection limit 0.1 mg / kg, no detection means no metal residue.

[0119] Table 1

[0120]

[0121] The test results above show that the antibacterial finishing agent prepared in Examples 1-3 of this invention, after treating cotton fabrics, still maintains an antibacterial rate of over 93% after 50 standard water washes, with no metal residue, a soft hand feel, and a soil degradation rate of >80% after 180 days, which is significantly better than the three comparative examples, meeting the requirements of green, durable, and safe integration.

[0122] The antibacterial rate of Comparative Example 1 decreased significantly after washing (65.2%), proving that the citric acid-chitosan oligosaccharide crosslinking agent is the key to water resistance.

[0123] Comparative Example 2 showed an antibacterial rate of only 78.4%, indicating that chitosan alone is insufficient to achieve efficient antibacterial activity, and multiple grafting synergy is essential.

[0124] Although the antibacterial rate of Comparative Example 3 was similar to that of the Example, its stiffness increased, its degradation rate dropped sharply, and Ag 28mg / kg was detected, highlighting the advantages of the metal-free system in terms of feel and environmental protection.

[0125] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An antibacterial finishing agent, characterized by, consists of the following raw materials by weight percentage: chitosan-phytic acid-gallic acid graft copolymer 15%-25%, citric acid-chitooligosaccharide crosslinking agent 1%-3%, polyglutamic acid sodium 0.5%-2%, natural surfactant 0.1%-0.5%, and the balance is water.

2. The antimicrobial finish according to claim 1, characterized in that, The chitosan-phytic acid-gallic acid graft copolymer is prepared by the following method: S1. Dissolve chitosan in 1wt% acetic acid solution, add 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide, and adjust the pH of the system to 5.5-6 with a pH adjuster; S2. Dissolve phytic acid in water to prepare a 50wt% aqueous solution based on phytic acid, adjust the pH to 6-6.5 with NaOH, and then drop into the above chitosan solution within 10 min, stir at 50-60℃ for 1-2h; S3. Dissolve gallic acid in water to prepare a 5-10wt% aqueous solution, adjust the pH to 6.5-7 with NaOH, and then drop into the reaction solution of step S2 within 10 min, stir at 50-60℃ for 1-2h, add ethanol to precipitate the product, filter, wash with ethanol, and dry at 50-60℃ under vacuum to obtain chitosan-phytic acid-gallic acid graft copolymer powder.

3. The antimicrobial finish according to claim 2, characterized in that, The molecular weight of the chitosan is 50-200kDa, and the degree of deacetylation is ≥85%.

4. The antimicrobial finish according to claim 2, characterized in that, The pH adjuster in step S1 is one of NaOH or hydrochloric acid; the mass ratio of chitosan to acetic acid solution is (2-3):100; and the mass ratio of chitosan, 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride, and N-hydroxysuccinimide is 1:(0.9-1):(0.5-0.6).

5. The antimicrobial finish according to claim 2, wherein, The mass ratio of chitosan, phytic acid, and gallic acid is 1:(0.5-0.6):(0.3-0.4).

6. The antimicrobial finish according to claim 1, wherein, The citric acid-chitooligosaccharide crosslinking agent is prepared by the following method: S4. Add chitooligosaccharide, citric acid, and sodium hypophosphite into a reaction kettle, mix, add deionized water, stir at 100-200rpm for 3-5min to form a uniform wet slurry; S5. Raise the temperature of the reaction kettle to 90-95℃, vacuum to -0.07~-0.08MPa, and dehydrate for 20-30min; continue to raise the temperature to 110-115℃, and maintain the vacuum degree at -0.08~-0.09MPa, and melt for 20-30min; S6. Cool, discharge, crush, pass through a 200 mesh sieve, and obtain citric acid-chitooligosaccharide crosslinking agent powder with a water content of ≤3%.

7. The antimicrobial finish according to claim 6, characterized in that, In step S4, the degree of deacetylation of chitooligosaccharide is ≥85%, and the molecular weight is 1-2kDa; the mass ratio of chitooligosaccharide, citric acid, and sodium hypophosphite is 1:(0.8-1.2):(0.02-0.03); and the mass of deionized water added is 15%-20% of the total mass of chitooligosaccharide and citric acid.

8. The antimicrobial finish according to claim 1, wherein, The natural surfactant is at least one selected from saponins and sophorolipids, and the molecular weight of the polyglutamic acid sodium is 50-300kDa.

9. A process for the preparation of the antibacterial finish as claimed in any one of claims 1 to 8, characterized in that, comprises the following steps: According to the formula, the chitosan-phytic acid-gallic acid graft copolymer, citric acid-chitooligosaccharide crosslinking agent, polyglutamic acid sodium, natural surfactant and water are mixed uniformly, the pH is adjusted to 6-6.5, and the reaction is carried out at 70-80°C and 200-300rpm for 1-2h, and then cooled to room temperature to obtain an antibacterial finishing agent.

10. Use of an antibacterial finish according to any one of claims 1 to 8 in a textile, characterized in that, The textile is finished by using padding-curing process, including the following steps: a) preparing working solution: diluting the antibacterial finishing agent with deionized water to 5-20g / L, and adjusting the pH to 6.0-6.5 with 0.1mol / L NaOH or 0.1mol / L HCl; b) padding: immersing the textile in the working solution with bath ratio of 1:10-1:20, double padding and double rolling, rolling pressure of 0.05-0.10MPa, and controlling the belt liquid rate of 70-100%; c) pre-drying: hot air pre-drying at 90-100°C for 2-3min; d) curing: curing at 150-160°C for 2-3min; e) post-treatment: cooling at room temperature, washing and drying, to obtain an antibacterial textile with washing resistance ≥50 times and inhibition rate ≥90%; The textile is pure cotton, pure hemp, pure silk or any proportion of blended fabric.

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