A sulfonium salt grafted modified long-lasting antibacterial cotton fiber and its preparation method

Abstract

The invention discloses a preparation method of a sulfonium salt grafted modified long-lasting antibacterial cotton fiber, comprising the following steps: (1) uniformly mixing polycarboxylic acid, sodium phosphate, disodium hydrogen phosphate, sodium hypophosphite and water to obtain a modified solution; (2) taking a certain amount of cotton fiber and completely immersing and dispersing the modified solution, reacting at 40-100° C. for 0.5-5 h to obtain a modified cotton fiber having a carboxyl group on the surface; (3) adding octadecyl thioether and iodomethane to an N,N-dimethylformamide / water solution, reacting for 24-48 h to obtain a solution; (4) dialyzing the solution in a 0.1 mol / L sodium chloride solution for 24 h, and then dialyzing it in deionized water for 24 h; (5) freeze-drying the dialyzed solution for 48 h to obtain an alkyl sulfonium salt; (6) immersing the modified cotton fiber in an alkaline aqueous solution, adding the alkyl sulfonium salt, and stirring the reaction at 40-80° C. for 1-4 h; and (7) obtaining the sulfonium salt grafted antibacterial cotton fiber. The cotton fiber of the present invention has long-lasting antibacterial properties while taking into account the mechanical properties of the cotton fiber and good biological safety.

Description

Technical Field

[0001] The invention belongs to the technical field of functional fibers, and in particular relates to a sulfonium salt grafted modified long-lasting antibacterial cotton fiber and a preparation method thereof. Background Art

[0002] With the rapid development of science and technology, people are placing higher demands on the hygienic properties of textiles. Cotton fiber, a natural textile material widely used since ancient times, boasts excellent moisture absorption, warmth retention, comfort, and low cost, making it an integral part of everyday life and production. However, natural cotton fiber lacks antibacterial properties, limiting its application in a wider range of fields. Therefore, a key research direction in cotton fiber modification is to enhance its antibacterial properties and reduce bacterial damage to the human body.

[0003] Many achievements have been made in the antibacterial modification of cotton fibers. Chinese patent CN115029925A combines sweet basil extract, coptis root extract, persimmon calyx extract, citronella essential oil, and clove essential oil in appropriate proportions to create herbal essential oil microcapsules. The cotton fibers are then scoured and treated to produce mosquito-repellent, antibacterial, and mildew-resistant cotton fibers. However, this treatment method limits the content of herbal antibacterial components in the modified cotton fibers, hindering the durability of the modified cotton fibers' antibacterial and antiviral properties.

[0004] Chinese patent CN114182530A uses etching to create hollow cotton fibers, which are then soaked to produce antibacterial and deodorizing cotton fibers adsorbed with seaweed polysaccharides, tea polyphenols, and zinc ions. This treatment significantly damages the modified cotton fibers, affecting their mechanical properties and hindering spinning.

[0005] Chinese patent CN113089151B describes a cotton core yarn with a soluble fiber core layer. After setting, the core yarn is dissolved and the resulting cotton shell yarn is immersed in an antibacterial finishing solution composed of quaternary ammonium salts and aloe vera extract. The resulting three-dimensional antibacterial yarn contains cotton fibers and has a rich, soft texture. However, the binding between the added substance and the cotton fibers is poor, affecting the durability of the cotton fibers' antibacterial properties.

[0006] To sum up, the existing antibacterial treatment technologies for cotton fibers all have certain defects, and most of them have long processes, complex techniques, and high costs. Therefore, how to make cotton fibers effectively obtain long-term antibacterial properties while taking into account the basic characteristics of cotton fibers such as mechanical properties, and being able to significantly shorten the process flow, lower the technical threshold, and significantly improve production efficiency has become a difficult problem that technicians in the field of functional fibers urgently need to solve. Summary of the Invention

[0007] In view of the shortcomings of the existing technology, the technical problem to be solved by the present invention is to provide a long-lasting antibacterial cotton fiber modified by sulfonium salt grafting and a preparation method thereof, which enables the cotton fiber to effectively obtain long-lasting antibacterial properties while taking into account the mechanical properties of the cotton fiber and good biological safety.

[0008] To solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing a long-lasting antibacterial cotton fiber grafted with a sulfonium salt, comprising the following steps:

[0009] 1. Cotton fiber modification:

[0010] (1) Mix polycarboxylic acid, sodium phosphate, disodium hydrogen phosphate, sodium hypophosphite and water to obtain a modified solution, which is then set aside;

[0011] (2) Taking a certain amount of cotton fiber and completely immersing it in the modified solution, stirring it under magnetic stirring at 40-100 ° C for 0.5-5 hours to obtain modified cotton fiber with carboxyl groups on the surface;

[0012] 2. Preparation of alkyl sulfonium salts:

[0013] (3) Add octadecyl thioether and methyl iodide to N,N-dimethylformamide / water solution and react for 24-48 hours to obtain a solution;

[0014] (4) The resulting solution was dialyzed against a 0.1 mol / L sodium chloride solution for 24 h, and then dialyzed against deionized water for 24 h;

[0015] (5) The dialyzed solution was freeze-dried for 48 h to obtain an alkyl sulfonium salt;

[0016] 3. Sulfonium salt grafted cotton fiber:

[0017] (6) Soaking the modified cotton fiber obtained in step (2) in an alkaline aqueous solution, adding the alkyl sulfonium salt obtained in step (5), and stirring the reaction at 40-80° C. for 1-4 hours;

[0018] (7) Obtain sulfonium salt grafted antibacterial cotton fiber.

[0019] The preparation method of the above-mentioned sulfonium salt grafted modified long-lasting antibacterial cotton fiber, in the step (1), the polycarboxylic acid is malic acid or citric acid, and the mass ratio of cotton fiber, water, malic acid or citric acid, sodium phosphate, disodium hydrogen phosphate, and sodium hypophosphite is 6:100:10-25:0.5:0.8:5.

[0020] The preparation method of the above-mentioned sulfonium salt grafted modified long-lasting antibacterial cotton fiber, in the step (1), the polycarboxylic acid is succinic acid or tartaric acid, and the mass ratio of cotton fiber, water, succinic acid or tartaric acid, sodium phosphate, disodium hydrogen phosphate, and sodium hypophosphite is 6:100:15-30:0.5:0.8:5.

[0021] In the above-mentioned method for preparing the long-lasting antibacterial cotton fiber modified by grafting of sulfonium salt, in the step (2), the cotton fiber is reacted in the modified solution at 80° C. with magnetic stirring for 1 hour.

[0022] In the above-mentioned method for preparing the long-lasting antibacterial cotton fiber grafted with sulfonium salt, in step (3), the mass ratio of octadecyl sulfide to methyl iodide is 1:1-5, and the mass ratio of the N,N-dimethylformamide / water solution is 1:0.5-1.5.

[0023] In the above-mentioned method for preparing the long-lasting antibacterial cotton fiber grafted with sulfonium salt, in step (6), the pH value of the alkaline aqueous solution is 9.5-10.5, and the mass ratio of alkyl sulfonium salt, cotton fiber and water is 0.5:6:100.

[0024] In the above-mentioned method for preparing the long-lasting antibacterial cotton fiber modified by grafting of sulfonium salt, in the step (6), the modified cotton fiber is immersed in an alkaline aqueous solution and stirred at 50° C. for 3 hours.

[0025] In the above-mentioned method for preparing the long-lasting antibacterial cotton fiber grafted with sulfonium salt, the mass ratio of octadecyl sulfide to methyl iodide is 1:3, and the ratio of N,N-dimethylformamide / water solution is 1:0.8.

[0026] In the above-mentioned method for preparing the long-lasting antibacterial cotton fiber grafted and modified with sulfonium salt, in step (6), the pH value of the alkaline aqueous solution is 10.

[0027] A sulfonium salt grafted modified long-lasting antibacterial cotton fiber is prepared by the above-mentioned preparation method.

[0028] The advantages of the long-lasting antibacterial cotton fiber modified by sulfonium salt grafting of the present invention and its preparation method are as follows: the main component of cotton fiber is cellulose, and under the catalytic action of sodium phosphate, disodium hydrogen phosphate, and sodium hypophosphite, the active hydroxyl groups in cellulose react with the carboxylic acid in the polycarboxylic acid to obtain a modified cotton fiber with a carboxyl group on the surface. At the same time, octadecyl thioether reacts with methyl iodide to generate a positively charged alkyl sulfonium salt, and then in an alkaline environment, the modified cotton fiber exposes the negatively charged oxygen in the carbonyl group, and the two are connected together by the electrostatic adsorption effect to obtain an antibacterial modified cotton fiber. Therefore, the sulfonium salt compound is directly grafted on the surface of the cotton fiber, which can effectively obtain antibacterial properties of the cotton fiber while taking into account the basic properties of the cotton fiber such as mechanical properties and hand feel, and can significantly shorten the process flow, reduce the technical threshold, and significantly improve production efficiency. The present invention adopts the sulfonium salt surface grafting method to give the cotton fiber a significant antibacterial effect, while ensuring the basic properties of the cotton fiber in all aspects, simplifying the processing flow, and having obvious social benefits and economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the reaction mechanism of sulfonium salt modified antibacterial cotton fiber of the present invention;

[0030] Figure 2 This is an electron microscope photo of the antibacterial cotton fiber obtained under 25% malic acid modification conditions;

[0031] Figure 3 This is an electron microscope photo of the antibacterial cotton fiber obtained under 25% citric acid modification conditions;

[0032] Figure 4 This is an electron microscope photo of the antibacterial cotton fiber obtained under 30% succinic acid modification conditions;

[0033] Figure 5 This is an electron microscope photograph of the antibacterial cotton fiber obtained under 30% tartaric acid modification conditions. DETAILED DESCRIPTION

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] In this disclosure, unless otherwise indicated, directional terms such as "upper" and "lower" generally refer to the upper and lower parts of a device in actual use or operation, specifically in the directions of the drawings in the accompanying drawings; whereas "inner" and "outer" refer to the outline of the device. Furthermore, in the description of this application, the term "including" means "including but not limited to." Terms such as first, second, and third are used merely as designations and do not impose numerical requirements or establish a sequence. The term "plurality" means "two or more."

[0036] like Figure 1As shown, a method for preparing a long-lasting antibacterial cotton fiber modified by grafting of sulfonium salt comprises the following steps:

[0037] 1. Cotton fiber modification:

[0038] (1) Mix polycarboxylic acid, sodium phosphate, disodium hydrogen phosphate, sodium hypophosphite and water to obtain a modified solution, which is then set aside;

[0039] (2) A certain amount of cotton fiber is completely immersed and dispersed in the modified solution, and the solution is stirred under magnetic stirring at 40-100°C for 0.5-5 hours to allow the active hydroxyl groups in the cellulose to undergo esterification with the carboxylic acid to obtain modified cotton fibers with carboxyl groups on the surface;

[0040] 2. Preparation of alkyl sulfonium salts:

[0041] (3) Add octadecyl thioether and methyl iodide to N,N-dimethylformamide / water solution and react for 24-48 hours to obtain a solution;

[0042] (4) The resulting solution was dialyzed against a 0.1 mol / L sodium chloride solution for 24 h, and then dialyzed against deionized water for 24 h;

[0043] (5) The dialyzed solution was freeze-dried for 48 h to obtain an alkyl sulfonium salt;

[0044] 3. Sulfonium salt grafted cotton fiber:

[0045] (6) Soaking the modified cotton fiber obtained in step (2) in an alkaline aqueous solution to expose the electronegative oxygen in the carbonyl functional group, adding the alkyl sulfonium salt obtained in step (5), stirring and reacting at 40-80° C. for 1-4 hours, and utilizing ionic electrostatic adsorption to adsorb the sulfonium salt on the surface of the modified fiber;

[0046] (7) Obtain sulfonium salt grafted antibacterial cotton fiber.

[0047] The N,N-dimethylformamide / water solution is a mixed solution of N,N-dimethylformamide and pure water in a weight ratio of 1:0.8.

[0048] The sulfonium salt grafted antibacterial cotton fiber prepared by the above method of the present invention has three free hydroxyl groups in each glucose unit in the molecular structure of cellulose, the main component of cotton fiber. Based on the dehydration between the polycarboxylic acid and the hydroxyl group of cellulose under the catalysis of sodium hypophosphite, the polycarboxylic acid with a carboxyl group is grafted into the cellulose structure, and then the negatively charged carbonyl group is ionized in an alkaline environment. The positively charged sulfonium salt is grafted on the fiber surface by utilizing the electrostatic adsorption effect. The carboxyl group connecting the cellulose and the sulfonium salt is formed by an esterification reaction. The sulfonium salt and the carbonyl group are connected by electrostatic adsorption, making the molecular structure of the prepared antibacterial cotton fiber more solid, thereby achieving long-term antibacterial properties. The cotton fiber described in the present invention includes cotton bulk fiber or products containing cotton bulk fiber, specifically including cotton yarn or cotton blended yarn prepared from cotton bulk fiber through processes such as carding, pre-drawing, strip and winding, drawing, roving, spun yarn, and bobbin. The preparation method of the present invention can be widely applied to the antibacterial modification of cellulose-based fibers, such as cotton fibers, hemp fibers (flax, hemp), viscose fibers, modal fibers, and the like.

[0049] The present application will be described in detail below through specific examples. The following examples are only some examples of the present application and are not limitations of the present application.

[0050] Example 1

[0051] A method for preparing a long-lasting antibacterial cotton fiber grafted with a sulfonium salt, characterized by comprising the following steps:

[0052] 1. Cotton fiber modification:

[0053] (1) Mix polycarboxylic acid, sodium phosphate, disodium hydrogen phosphate, sodium hypophosphite and water to obtain a modified solution for later use; wherein the polycarboxylic acid is malic acid or citric acid, and the mass ratio of cotton fiber, water, malic acid or citric acid, sodium phosphate, disodium hydrogen phosphate and sodium hypophosphite is 6:100:10:0.5:0.8:5.

[0054] (2) A certain amount of cotton fiber was completely immersed and dispersed in the modified solution, and the solution was stirred under magnetic stirring at 40°C for 5 h to obtain modified cotton fiber with carboxyl groups on the surface;

[0055] 2. Preparation of alkyl sulfonium salts:

[0056] (3) Add octadecyl sulfide and iodomethane to N,N-dimethylformamide / water solution and react for 24 hours to obtain a solution; wherein the mass ratio of octadecyl sulfide to iodomethane is 1:1, and the mass ratio of the N,N-dimethylformamide / water solution is 1:0.5.

[0057] (4) The resulting solution was dialyzed against a 0.1 mol / L sodium chloride solution for 24 h, and then dialyzed against deionized water for 24 h;

[0058] (5) The dialyzed solution was freeze-dried for 48 h to obtain an alkyl sulfonium salt;

[0059] 3. Sulfonium salt grafted cotton fiber:

[0060] (6) Soaking the modified cotton fiber obtained in step (2) in an alkaline aqueous solution, adding the alkyl sulfonium salt obtained in step (5), and stirring the reaction at 40° C. for 4 hours; wherein the pH value of the alkaline aqueous solution is 9.5, and the mass ratio of the alkyl sulfonium salt, cotton fiber, and water is 0.5:6:100.

[0061] (7) Obtain sulfonium salt grafted antibacterial cotton fiber.

[0062] Example 2

[0063] A method for preparing a long-lasting antibacterial cotton fiber grafted with a sulfonium salt, characterized by comprising the following steps:

[0064] 1. Cotton fiber modification:

[0065] (1) Mix polycarboxylic acid, sodium phosphate, disodium hydrogen phosphate, sodium hypophosphite and water to obtain a modified solution for later use; wherein the polycarboxylic acid is malic acid or citric acid, and the mass ratio of cotton fiber, water, malic acid or citric acid, sodium phosphate, disodium hydrogen phosphate and sodium hypophosphite is 6:100:20:0.5:0.8:5.

[0066] (2) A certain amount of cotton fiber was completely immersed and dispersed in the modified solution, and the solution was stirred under magnetic stirring at 80°C for 1 hour to obtain modified cotton fiber with carboxyl groups on the surface;

[0067] 2. Preparation of alkyl sulfonium salts:

[0068] (3) Adding octadecyl sulfide and iodomethane to an N,N-dimethylformamide / water solution and reacting for 36 hours to obtain a solution; wherein the mass ratio of octadecyl sulfide to iodomethane is 1:3, and the mass ratio of the N,N-dimethylformamide / water solution is 1:0.8.

[0069] (4) The resulting solution was dialyzed against a 0.1 mol / L sodium chloride solution for 24 h, and then dialyzed against deionized water for 24 h;

[0070] (5) The dialyzed solution was freeze-dried for 48 h to obtain an alkyl sulfonium salt;

[0071] 3. Sulfonium salt grafted cotton fiber:

[0072] (6) Soaking the modified cotton fiber obtained in step (2) in an alkaline aqueous solution, adding the alkyl sulfonium salt obtained in step (5), and stirring the reaction at 50° C. for 3 h; wherein the pH value of the alkaline aqueous solution is 10, and the mass ratio of the alkyl sulfonium salt, the cotton fiber, and water is 0.5:6:100.

[0073] (7) Obtain sulfonium salt grafted antibacterial cotton fiber.

[0074] Example 3

[0075] A method for preparing a long-lasting antibacterial cotton fiber grafted with a sulfonium salt, characterized by comprising the following steps:

[0076] 1. Cotton fiber modification:

[0077] (1) Mix polycarboxylic acid, sodium phosphate, disodium hydrogen phosphate, sodium hypophosphite and water to obtain a modified solution for later use; wherein the polycarboxylic acid is malic acid or citric acid, and the mass ratio of cotton fiber, water, malic acid or citric acid, sodium phosphate, disodium hydrogen phosphate and sodium hypophosphite is 6:100:25:0.5:0.8:5.

[0078] (2) A certain amount of cotton fiber was completely immersed and dispersed in the modified solution, and the solution was reacted under magnetic stirring at 100°C for 0.5 h to obtain modified cotton fiber with carboxyl groups on the surface;

[0079] 2. Preparation of alkyl sulfonium salts:

[0080] (3) Adding octadecyl sulfide and iodomethane to an N,N-dimethylformamide / water solution and reacting for 48 hours to obtain a solution; wherein the mass ratio of octadecyl sulfide to iodomethane is 1:1-5, and the mass ratio of the N,N-dimethylformamide / water solution is 1:0.5-1.5.

[0081] (4) The resulting solution was dialyzed against a 0.1 mol / L sodium chloride solution for 24 h, and then dialyzed against deionized water for 24 h;

[0082] (5) The dialyzed solution was freeze-dried for 48 h to obtain an alkyl sulfonium salt;

[0083] 3. Sulfonium salt grafted cotton fiber:

[0084] (6) Soaking the modified cotton fiber obtained in step (2) in an alkaline aqueous solution, adding the alkyl sulfonium salt obtained in step (5), and stirring the reaction at 80° C. for 1 hour; wherein the pH value of the alkaline aqueous solution is 10.5, and the mass ratio of the alkyl sulfonium salt, the cotton fiber, and water is 0.5:6:100.

[0085] (7) Obtain sulfonium salt grafted antibacterial cotton fiber.

[0086] Example 4

[0087] The same parts as those in Example 2 are not repeated here. The difference between this embodiment and Example 2 is that: in step (1), the polycarboxylic acid is succinic acid or tartaric acid, and the mass ratio of cotton fiber, water, succinic acid or tartaric acid, sodium phosphate, disodium hydrogen phosphate, and sodium hypophosphite is 6:100:15:0.5:0.8:5.

[0088] Example 5

[0089] The same parts as those in Example 2 are not repeated here. The difference between this embodiment and Example 2 is that: in step (1), the polycarboxylic acid is succinic acid or tartaric acid, and the mass ratio of cotton fiber, water, succinic acid or tartaric acid, sodium phosphate, disodium hydrogen phosphate, and sodium hypophosphite is 6:100:25:0.5:0.8:5.

[0090] Example 6

[0091] The same parts as those in Example 2 are not repeated here. The difference between this embodiment and Example 2 is that: in step (1), the polycarboxylic acid is succinic acid or tartaric acid, and the mass ratio of cotton fiber, water, succinic acid or tartaric acid, sodium phosphate, disodium hydrogen phosphate, and sodium hypophosphite is 6:100:30:0.5:0.8:5.

[0092] The present invention utilizes the sulfonium salt grafting modification method to obtain long-lasting antibacterial cotton fibers under different polycarboxylic acid and dosage conditions. The test results of the grafting status, antibacterial properties, water resistance and antibacterial properties, biosafety, and mechanical properties are as follows:

[0093] 1. Grafting status, antibacterial properties, water resistance, antibacterial properties, and biosafety:

[0094] Preparation process of alkyl sulfonium salt of the present invention

[0095] Prepare 20 mL of N,N-dimethylformamide / water solution with a volume ratio of 1:0.8, add 0.6 g of octadecyl sulfide and 1.8 mL of iodomethane, stir and react for 48 hours, then dialyze in 0.1 mol / L sodium chloride solution and deionized water for 24 hours, and finally freeze-dry for 48 hours to obtain the alkyl sulfonium salt.

[0096] 1. Polycarboxylic acid is malic acid

[0097] (1) The mass ratio of cotton fiber, water, malic acid, sodium phosphate, disodium hydrogen phosphate and sodium hypophosphite is 6:100:10:0.5:0.8:5.

[0098] 18 g of cotton fiber was dispersed in 300 g of pure water, and 30 g of malic acid, 1.5 g of sodium phosphate, 2.4 g of disodium hydrogen phosphate, and 15 g of sodium hypophosphite were dissolved in the water. The mixture was magnetically stirred at 80 ° C for 1 hour. The fiber was then taken out and rinsed three times, divided into 3 equal parts, 6 g each, and transferred to 100 g of pure water respectively. The pH was adjusted to 10 with 0.1 mol / L sodium hydroxide solution, and 0.5 g of alkyl sulfonium salt was added to each part. The mixture was stirred and reacted at 50 ° C for 3 hours to obtain 10% malic acid-modified sulfonium salt-grafted antibacterial cotton fiber.

[0099] EDX elemental analysis was performed on the surface of the antibacterial fiber, and the S element content (atomic%) was measured to be 0.56%, indicating that the alkyl sulfonium salt has been grafted on the surface of the cotton fiber. The antibacterial properties and water-washing resistance of the sulfonium salt grafted modified antibacterial cotton fiber were tested in accordance with FZ / T 73023-2006. At the same time, the same batch of antibacterial cotton fibers were stored in a cool and ventilated place, and the antibacterial performance was tested after standing for 6 months and 12 months. The antibacterial rate is shown in Table 1. All samples showed water-washing resistance and long-lasting antibacterial effects, but the overall antibacterial effect was poor. The samples were subjected to in vitro cytotoxicity tests in accordance with GBT 16886.5-2017, and the fibroblast survival rate was 99.8%, indicating that the sample was non-cytotoxic.

[0100] Table 1 Antibacterial effect of 10% malic acid modified sulfonium salt grafted antibacterial cotton fiber

[0101] Antibacterial rate (%) Escherichia coli Staphylococcus aureus Candida albicans 10% malic acid 67.8 68.0 62.7 10% Malic Acid - After 6 months 67.5 68.0 62.3 10% Malic Acid - After 12 months 66.2 67.2 61.6 10% malic acid-washed 50 times 66,9 67.7 61.4 10% malic acid-washed 100 times 65.1 66.5 60.3

[0102] (2) The mass ratio of cotton fiber, water, malic acid, sodium phosphate, disodium hydrogen phosphate, and sodium hypophosphite is 6:100:15:0.5:0.8:5.

[0103] 30g of malic acid was replaced with 45g of malic acid to obtain 15% malic acid-modified sulfonium salt grafted antibacterial cotton fiber. EDX elemental analysis and a series of antibacterial performance tests were performed on it. The S element content (atomic%) was measured to be 0.79%, indicating that the alkyl sulfonium salt had been grafted on the cotton fiber surface and the grafting rate was improved. The antibacterial rate is shown in Table 2. All samples showed water resistance and long-lasting antibacterial effect, but the overall antibacterial effect was poor. The samples were subjected to in vitro cytotoxicity tests, and the fibroblast survival rate was 99.6%, indicating that the sample was non-cytotoxic.

[0104] Table 2 Antibacterial effect of 15% malic acid modified sulfonium salt grafted antibacterial cotton fiber

[0105] Antibacterial rate (%) Escherichia coli Staphylococcus aureus Candida albicans 15% malic acid 80.7 78.6 71.2 15% Malic Acid - After 6 months 80.0 78.1 70.7 15% Malic Acid - After 12 months 79.4 76.1 69.2 15% malic acid-washed 50 times 79.8 77.7 70.9 15% malic acid-washed 100 times 78.2 76.7 69.7

[0106] (3) The mass ratio of cotton fiber, water, malic acid, sodium phosphate, disodium hydrogen phosphate, and sodium hypophosphite is 6:100:20:0.5:0.8:5.

[0107] 30g of malic acid was replaced with 60g of malic acid to obtain 20% malic acid-modified sulfonium salt grafted antibacterial cotton fiber. EDX elemental analysis and a series of antibacterial performance tests were performed on it. The S element content (atomic%) was measured to be 0.91%, indicating that the alkyl sulfonium salt had been grafted on the cotton fiber surface, and the grafting rate was further improved. The antibacterial rate is shown in Table 3. All samples showed water resistance and long-lasting antibacterial effect, and the antibacterial level reached AAA level. The samples were subjected to in vitro cytotoxicity tests, and the fibroblast survival rate was 99.7%, indicating that the sample was non-cytotoxic.

[0108] Table 3 Antibacterial effect of 20% malic acid modified sulfonium salt grafted antibacterial cotton fiber

[0109] Antibacterial rate (%) Escherichia coli Staphylococcus aureus Candida albicans 20% malic acid 90.5 91.5 87.5 20% Malic Acid - After 6 months 90.1 91.3 87.1 20% Malic Acid - After 12 months 89.1 90.2 86.2 20% malic acid-washed 50 times 90.4 91.4 87.4 20% malic acid-washed 100 times 89.6 90.1 86.7

[0110] (4) The mass ratio of cotton fiber, water, malic acid, sodium phosphate, disodium hydrogen phosphate, and sodium hypophosphite is 6:100:25:0.5:0.8:5.

[0111] 30g of malic acid was replaced with 75g of malic acid to obtain 25% malic acid-modified sulfonium salt grafted antibacterial cotton fiber. EDX elemental analysis and a series of antibacterial performance tests were performed on it. The S element content (atomic%) was measured to be 0.10%, indicating that the alkyl sulfonium salt had been grafted on the cotton fiber surface, and the grafting rate was the highest in the malic acid-modified cotton fiber group. The antibacterial rate is shown in Table 4. All samples showed water resistance and long-lasting antibacterial effects, and the antibacterial level reached AAA. The samples were subjected to in vitro cytotoxicity tests, and the fibroblast survival rate was 99.5%, indicating that the sample was non-cytotoxic.

[0112] Table 4 Antibacterial effect of 25% malic acid modified sulfonium salt grafted antibacterial cotton fiber

[0113]

[0114]

[0115] 2. Polycarboxylic acid is citric acid

[0116] (1) The mass ratio of cotton fiber, water, citric acid, sodium phosphate, disodium hydrogen phosphate, and sodium hypophosphite is 6:100:10:0.5:0.8:5.

[0117] 18 g of cotton fiber was dispersed in 300 g of pure water, and 30 g of citric acid, 1.5 g of sodium phosphate, 2.4 g of disodium hydrogen phosphate, and 15 g of sodium hypophosphite were dissolved in the water. The mixture was magnetically stirred at 80 ° C for 1 hour. The fiber was then taken out and rinsed three times, divided into 3 equal parts, 6 g each, and transferred to 100 g of pure water respectively. The pH was adjusted to 10 with 0.1 mol / L sodium hydroxide solution, and 0.5 g of alkyl sulfonium salt was added to each part. The mixture was stirred and reacted at 50 ° C for 3 hours to obtain 10% citric acid-modified sulfonium salt grafted antibacterial cotton fiber.

[0118] EDX elemental analysis was performed on the surface of the antibacterial fiber, and the S element content (atomic%) was measured to be 0.86%, indicating that the alkyl sulfonium salt has been grafted on the surface of the cotton fiber. The antibacterial properties and water-washing resistance of the sulfonium salt grafted modified antibacterial cotton fiber were tested in accordance with FZ / T 73023-2006. At the same time, the antibacterial cotton fibers of the same batch were stored in a cool and ventilated place, and the antibacterial performance was tested after standing for 6 months and 12 months. The antibacterial rate is shown in Table 5. All samples showed water-washing resistance and long-lasting antibacterial effects, but the overall antibacterial effect was poor. The samples were subjected to in vitro cytotoxicity tests in accordance with GBT 16886.5-2017, and the fibroblast survival rate was 99.7%, indicating that the sample was non-cytotoxic.

[0119] Table 5 Antibacterial effect of 10% citric acid modified sulfonium salt grafted antibacterial cotton fiber

[0120] Antibacterial rate (%) Escherichia coli Staphylococcus aureus Candida albicans 10% citric acid 79.2 77.6 69.2 10% citric acid - after 6 months 79.2 77.2 68.3 10% citric acid - after 12 months 78.6 76.5 66.1 10% citric acid-water wash 50 times 78.5 77.4 68.8 10% citric acid-washed 100 times 77.7 76.8 68.0

[0121] (2) The mass ratio of cotton fiber, water, citric acid, sodium phosphate, disodium hydrogen phosphate, and sodium hypophosphite is 6:100:15:0.5:0.8:5.

[0122] 30g of citric acid was replaced with 45g of citric acid to obtain 15% citric acid-modified sulfonium salt grafted antibacterial cotton fiber. EDX elemental analysis and a series of antibacterial performance tests were performed on it. The S element content (atomic%) was measured to be 0.95%, indicating that the alkyl sulfonium salt had been grafted on the cotton fiber surface and the grafting rate was improved. The antibacterial rate is shown in Table 6. All samples showed water resistance and long-lasting antibacterial effect, and the antibacterial level reached AAA level. The samples were subjected to in vitro cytotoxicity tests, and the fibroblast survival rate was 99.5%, indicating that the sample was non-cytotoxic.

[0123] Table 6 Antibacterial effect of 15% citric acid modified sulfonium salt grafted antibacterial cotton fiber

[0124]

[0125]

[0126] (3) The mass ratio of cotton fiber, water, citric acid, sodium phosphate, disodium hydrogen phosphate, and sodium hypophosphite is 6:100:20:0.5:0.8:5.

[0127] 30g of citric acid was replaced with 60g of citric acid to obtain 20% citric acid-modified sulfonium salt grafted antibacterial cotton fiber. EDX elemental analysis and a series of antibacterial performance tests were performed on it. The S element content (atomic%) was measured to be 1.13%, indicating that the alkyl sulfonium salt had been grafted on the cotton fiber surface, and the grafting rate was further improved. The antibacterial rate is shown in Table 7. All samples showed water resistance and long-lasting antibacterial effect, and the antibacterial level reached AAA. The samples were subjected to in vitro cytotoxicity tests, and the fibroblast survival rate was 99.4%, indicating that the sample was non-cytotoxic.

[0128] Table 7 Antibacterial effect of 20% citric acid modified sulfonium salt grafted antibacterial cotton fiber

[0129] Antibacterial rate (%) Escherichia coli Staphylococcus aureus Candida albicans 20% citric acid ≥99.9 ≥99.9 ≥99.9 20% citric acid - after 6 months ≥99.9 ≥99.9 ≥99.9 20% citric acid - after 12 months ≥99.9 ≥99.9 ≥99.9 20% citric acid-wash 50 times ≥99.9 ≥99.9 ≥99.9 20% citric acid-washed 100 times ≥99.9 ≥99.9 ≥99.9

[0130] (4) The mass ratio of cotton fiber, water, citric acid, sodium phosphate, disodium hydrogen phosphate, and sodium hypophosphite is 6:100:25:0.5:0.8:5.

[0131] 30g of citric acid was replaced with 75g of citric acid to obtain 25% citric acid-modified sulfonium salt grafted antibacterial cotton fiber. EDX elemental analysis and a series of antibacterial performance tests were performed on it. The S element content (atomic%) was measured to be 1.32%, indicating that the alkyl sulfonium salt had been grafted on the cotton fiber surface, and the grafting rate was the highest in the citric acid modified cotton fiber group. The antibacterial rate is shown in Table 8. All samples showed water resistance and long-lasting antibacterial effect, and the antibacterial level reached AAA. The samples were subjected to in vitro cytotoxicity tests, and the fibroblast survival rate was 99.6%, indicating that the sample had no cytotoxicity.

[0132] Table 4 Antibacterial effect of 25% citric acid modified sulfonium salt grafted antibacterial cotton fiber

[0133] Antibacterial rate (%) Escherichia coli Staphylococcus aureus Candida albicans 25% citric acid ≥99.9 ≥99.9 ≥99.9 25% citric acid - after 6 months ≥99.9 ≥99.9 ≥99.9 25% citric acid - after 12 months ≥99.9 ≥99.9 ≥99.9 25% citric acid-wash 50 times ≥99.9 ≥99.9 ≥99.9 25% citric acid-washed 100 times ≥99.9 ≥99.9 ≥99.9

[0134] 3. Polycarboxylic acid is succinic acid

[0135] (1) The mass ratio of cotton fiber, water, succinic acid, sodium phosphate, disodium hydrogen phosphate and sodium hypophosphite is 6:100:15:0.5:0.8:5.

[0136] 18 g of cotton fiber was dispersed in 300 g of pure water, and 45 g of succinic acid, 1.5 g of sodium phosphate, 2.4 g of disodium hydrogen phosphate, and 15 g of sodium hypophosphite were dissolved in the water. The mixture was magnetically stirred at 80 ° C for 1 hour. The fiber was then taken out and rinsed three times, divided into 3 equal parts, 6 g each, and transferred to 100 g of pure water respectively. The pH was adjusted to 10 with 0.1 mol / L sodium hydroxide solution, and 0.5 g of alkyl sulfonium salt was added to each part. The mixture was stirred and reacted at 50 ° C for 3 hours to obtain 15% succinic acid-modified sulfonium salt-grafted antibacterial cotton fiber.

[0137] EDX elemental analysis was performed on the surface of the antibacterial fiber, and the S element content (atomic%) was measured to be 0.80%, indicating that the alkyl sulfonium salt has been grafted on the surface of the cotton fiber. The antibacterial properties and water-washing resistance of the sulfonium salt grafted modified antibacterial cotton fiber were tested in accordance with FZ / T 73023-2006. At the same time, the same batch of antibacterial cotton fibers were stored in a cool and ventilated place, and the antibacterial performance was tested after standing for 6 months and 12 months. The antibacterial rate is shown in Table 9. All samples showed water-washing resistance and long-lasting antibacterial effects, and the antibacterial level reached AAA. The samples were subjected to in vitro cytotoxicity testing in accordance with GBT 16886.5-2017, and the fibroblast survival rate was 99.5%, indicating that the sample was non-cytotoxic.

[0138] Table 9 Antibacterial effect of 15% succinic acid modified sulfonium salt grafted antibacterial cotton fiber

[0139] Antibacterial rate (%) Escherichia coli Staphylococcus aureus Candida albicans 15% succinic acid 81.6 84.7 70.5 15% Succinic Acid - After 6 months 80.8 84.6 70.4 15% Succinic Acid - After 12 months 80.1 83.8 69.5 15% succinic acid-washed 50 times 81.2 84.2 70.3 15% succinic acid-washed 100 times 80.4 83.9 70.0

[0140] (2) The mass ratio of cotton fiber, water, succinic acid, sodium phosphate, disodium hydrogen phosphate, and sodium hypophosphite is 6:100:20:0.5:0.8:5.

[0141] 45g of succinic acid was replaced with 60g of succinic acid to obtain 20% succinic acid-modified sulfonium salt grafted antibacterial cotton fiber. EDX elemental analysis and a series of antibacterial performance tests were performed on it. The S element content (atomic%) was measured to be 0.92%, indicating that the alkyl sulfonium salt had been grafted on the cotton fiber surface and the grafting rate was improved. The antibacterial rate is shown in Table 10. All samples showed water resistance and long-lasting antibacterial effect, and the antibacterial level reached AAA level. The samples were subjected to in vitro cytotoxicity tests, and the fibroblast survival rate was 99.7%, indicating that the sample was non-cytotoxic.

[0142] Table 10 Antibacterial effect of 20% amber-modified sulfonium salt grafted antibacterial cotton fiber

[0143] Antibacterial rate (%) Escherichia coli Staphylococcus aureus Candida albicans 20% succinic acid 93.2 91.5 88.6 20% Succinic Acid - After 6 months 92.6 92.6 86.4 20% Succinic Acid - After 12 months 92.1 90.2 87.2 20% succinic acid-washed 50 times 94.3 93.6 88.5 20% succinic acid-washed 100 times 92.8 93.5 88.3

[0144] (3) The mass ratio of cotton fiber, water, succinic acid, sodium phosphate, disodium hydrogen phosphate, and sodium hypophosphite is 6:100:25:0.5:0.8:5.

[0145] 45g of succinic acid was replaced with 75g of succinic acid to obtain 25% succinic acid-modified sulfonium salt grafted antibacterial cotton fiber. EDX elemental analysis and a series of antibacterial performance tests were performed on it. The S element content (atomic%) was measured to be 1.11%, indicating that the alkyl sulfonium salt had been grafted on the cotton fiber surface, and the grafting rate was further improved. The antibacterial rate is shown in Table 11. All samples showed water resistance and long-lasting antibacterial effect, and the antibacterial level reached AAA. The samples were subjected to in vitro cytotoxicity tests, and the fibroblast survival rate was 99.6%, indicating that the sample was non-cytotoxic.

[0146] Table 11 Antibacterial effect of 25% succinic acid modified sulfonium salt grafted antibacterial cotton fiber

[0147] Antibacterial rate (%) Escherichia coli Staphylococcus aureus Candida albicans 25% succinic acid ≥99.9 ≥99.9 ≥99.9 25% succinic acid - after 6 months ≥99.9 ≥99.9 ≥99.9 25% Succinic Acid - After 12 months ≥99.9 ≥99.9 ≥99.9 25% succinic acid-washed 50 times ≥99.9 ≥99.9 ≥99.9 25% succinic acid-washed 100 times ≥99.9 ≥99.9 ≥99.9

[0148] (4) The mass ratio of cotton fiber, water, succinic acid, sodium phosphate, disodium hydrogen phosphate, and sodium hypophosphite is 6:100:30:0.5:0.8:5.

[0149] 45g of succinic acid was replaced with 90g of succinic acid to obtain 30% succinic acid-modified sulfonium salt grafted antibacterial cotton fiber. EDX elemental analysis and a series of antibacterial performance tests were performed on it. The S element content (atomic%) was measured to be 1.32%, indicating that the alkyl sulfonium salt had been grafted on the cotton fiber surface, and the grafting rate was the highest in the succinic acid-modified cotton fiber group. The antibacterial rate is shown in Table 12. All samples showed water resistance and long-lasting antibacterial effect, and the antibacterial level reached AAA. The samples were subjected to in vitro cytotoxicity tests, and the fibroblast survival rate was 99.7%, indicating that the sample had no cytotoxicity.

[0150] Table 12 Antibacterial effect of 30% succinic acid modified sulfonium salt grafted antibacterial cotton fiber

[0151] Antibacterial rate (%) Escherichia coli Staphylococcus aureus Candida albicans 30% succinic acid ≥99.9 ≥99.9 ≥99.9 30% Succinic Acid - After 6 months ≥99.9 ≥99.9 ≥99.9 30% Succinic Acid - After 12 months ≥99.9 ≥99.9 ≥99.9 30% succinic acid-washed 50 times ≥99.9 ≥99.9 ≥99.9 30% succinic acid-washed 100 times ≥99.9 ≥99.9 ≥99.9

[0152] 4. Polycarboxylic acid is tartaric acid

[0153] (1) The mass ratio of cotton fiber, water, tartaric acid, sodium phosphate, disodium hydrogen phosphate and sodium hypophosphite is 6:100:15:0.5:0.8:5.

[0154] 18 g of cotton fiber was dispersed in 300 g of pure water, and 45 g of tartaric acid, 1.5 g of sodium phosphate, 2.4 g of disodium hydrogen phosphate, and 15 g of sodium hypophosphite were dissolved in the water. The mixture was magnetically stirred at 80 ° C for 1 hour. The fiber was then taken out and rinsed three times, divided into 3 equal parts, 6 g each, and transferred to 100 g of pure water respectively. The pH was adjusted to 10 with 0.1 mol / L sodium hydroxide solution, and 0.5 g of alkyl sulfonium salt was added to each part. The mixture was stirred and reacted at 50 ° C for 3 hours to obtain 15% tartaric acid-modified sulfonium salt grafted antibacterial cotton fiber.

[0155] EDX elemental analysis was performed on the surface of the antibacterial fiber, and the S element content (atomic%) was measured to be 0.84%, indicating that the alkyl sulfonium salt has been grafted on the surface of the cotton fiber. The antibacterial properties and water-washing resistance of the sulfonium salt grafted modified antibacterial cotton fiber were tested in accordance with FZ / T 73023-2006. At the same time, the antibacterial cotton fibers of the same batch were stored in a cool and ventilated place, and the antibacterial performance was tested after standing for 6 months and 12 months. The antibacterial rate is shown in Table 13. All samples showed water-washing resistance and long-lasting antibacterial effects, and the antibacterial level reached AAA. The samples were subjected to in vitro cytotoxicity testing in accordance with GBT 16886.5-2017, and the fibroblast survival rate was 99.7%, indicating that the sample was non-cytotoxic.

[0156] Table 13 Antibacterial effect of 15% tartaric acid modified sulfonium salt grafted antibacterial cotton fiber

[0157] Antibacterial rate (%) Escherichia coli Staphylococcus aureus Candida albicans 15% tartaric acid 83.5 82.8 72.5 15% tartaric acid - after 6 months 82.3 82.3 71.3 15% tartaric acid - after 12 months 82.0 81.5 70.9 15% tartaric acid-washed 50 times 83.2 82.6 72.0 15% tartaric acid-washed 100 times 81.5 81.5 70.4

[0158] (2) The mass ratio of cotton fiber, water, tartaric acid, sodium phosphate, disodium hydrogen phosphate, and sodium hypophosphite is 6:100:20:0.5:0.8:5.

[0159] 45g of tartaric acid was replaced with 60g of tartaric acid to obtain 20% tartaric acid-modified sulfonium salt grafted antibacterial cotton fiber. EDX elemental analysis and a series of antibacterial performance tests were performed on it. The S element content (atomic%) was measured to be 0.96%, indicating that the alkyl sulfonium salt had been grafted on the cotton fiber surface and the grafting rate was improved. The antibacterial rate is shown in Table 14. All samples showed water resistance and long-lasting antibacterial effect, and the antibacterial grade reached AAA. The samples were subjected to in vitro cytotoxicity tests, and the fibroblast survival rate was 99.5%, indicating that the sample had no cytotoxicity.

[0160] Table 14 Antibacterial effect of 20% tartaric acid modified sulfonium salt grafted antibacterial cotton fiber

[0161] Antibacterial rate (%) Escherichia coli Staphylococcus aureus Candida albicans 20% tartaric acid 94.7 93.9 91.6 20% tartaric acid - after 6 months 94.1 93.0 90.1 20% tartaric acid - after 12 months 92.9 92.5 89.6 20% tartaric acid-washed 50 times 93.7 92.6 90.7 20% tartaric acid-washed 100 times 92.4 92.0 89.2

[0162] (3) The mass ratio of cotton fiber, water, tartaric acid, sodium phosphate, disodium hydrogen phosphate, and sodium hypophosphite is 6:100:25:0.5:0.8:5.

[0163] 45g of tartaric acid was replaced with 75g of tartaric acid to obtain 25% tartaric acid-modified sulfonium salt grafted antibacterial cotton fiber. EDX elemental analysis and a series of antibacterial performance tests were performed on it. The S element content (atomic%) was measured to be 1.12%, indicating that the alkyl sulfonium salt had been grafted on the cotton fiber surface, and the grafting rate was further improved. The antibacterial rate is shown in Table 15. All samples showed water resistance and long-lasting antibacterial effect, and the antibacterial grade reached AAA. The samples were subjected to in vitro cytotoxicity test, and the fibroblast survival rate was 99.4%, and the sample was non-cytotoxic.

[0164] Table 15 Antibacterial effect of 25% tartaric acid modified sulfonium salt grafted antibacterial cotton fiber

[0165] Antibacterial rate (%) Escherichia coli Staphylococcus aureus Candida albicans 25% tartaric acid ≥99.9 ≥99.9 ≥99.9 25% tartaric acid - after 6 months ≥99.9 ≥99.9 99.6 25% tartaric acid - after 12 months ≥99.9 ≥99.9 99.1 25% tartaric acid-washed 50 times ≥99.9 ≥99.9 99.4 25% tartaric acid-washed 100 times ≥99.9 ≥99.9 98.8

[0166] (4) The mass ratio of cotton fiber, water, tartaric acid, sodium phosphate, disodium hydrogen phosphate, and sodium hypophosphite is 6:100:30:0.5:0.8:5.

[0167] 45g of tartaric acid was replaced with 90g of tartaric acid to obtain 30% tartaric acid-modified sulfonium salt grafted antibacterial cotton fiber. EDX elemental analysis and a series of antibacterial performance tests were performed on it. The measured S element content (atomic%) was 1.33%, indicating that the alkyl sulfonium salt had been grafted on the cotton fiber surface, and the grafting rate was the highest in the tartaric acid modified cotton fiber group. The antibacterial rate is shown in Table 16. All samples showed water resistance and long-lasting antibacterial effect, and the antibacterial grade reached AAA. The sample was subjected to in vitro cytotoxicity test, and the fibroblast survival rate was 99.5%, and the sample was non-cytotoxic.

[0168] Table 16 Antibacterial effect of 30% tartaric acid modified sulfonium salt grafted antibacterial cotton fiber

[0169] Antibacterial rate (%) Escherichia coli Staphylococcus aureus Candida albicans 30% tartaric acid ≥99.9 ≥99.9 ≥99.9 30% tartaric acid - after 6 months ≥99.9 ≥99.9 ≥99.9 30% tartaric acid - after 12 months ≥99.9 ≥99.9 ≥99.9 30% tartaric acid-washed 50 times ≥99.9 ≥99.9 ≥99.9 30% tartaric acid-washed 100 times ≥99.9 ≥99.9 ≥99.9

[0170] 2. Mechanical properties:

[0171] The surface morphologies of the sulfonium salt grafted antibacterial cotton fibers obtained after 25% malic acid modification, 25% citric acid modification, 30% succinic acid modification, and 30% tartaric acid modification are shown in Figure 2. Figure 2-5 As shown, all fibers maintained a smooth, continuous twisted structure, with no significant difference from natural cotton fibers. The four groups of modified sulfonium salt-grafted antibacterial cotton fibers were tested for breaking strength according to GB / T 13783-1992, with the results shown in Table 17.

[0172] Table 17 Breaking strength of ordinary cotton fibers and four kinds of antibacterial cotton fibers

[0173] Fiber status Average breaking strength (cN / tex) Average elongation at break (%) Ordinary cotton fiber 27.6 7.6 25% malic acid modified cotton fiber 26.5 7.2 25% citric acid modified cotton fiber 25.7 6.6 30% succinic acid modified cotton fiber 25.3 6.2 30% tartaric acid modified cotton fiber 25.5 6.5

[0174] From the above experimental results, it can be seen that by comparing the antibacterial rate, S element content, cell survival rate and electron microscope photos of cotton fibers obtained under different process parameters and treatment conditions in Table 1-16, it can be concluded that:

[0175] The sulfonium salt modified antibacterial cotton fiber provided by the present invention has excellent antibacterial properties and biosafety, and the antibacterial effect is not affected by time and water washing. As can be seen from Table 17, the surface morphology and mechanical properties of ordinary cotton fibers do not change significantly after antibacterial modification. This is because the alkyl sulfonium salt is only grafted to the side chains of cellulose macromolecules, without destroying the main chain structure of the cellulose molecules, and retains the original characteristics of cellulose to the greatest extent, that is, it still has a smooth surface morphology and high breaking strength. Through comparative analysis, in the pretreatment process of cotton fibers, the number of carboxyl groups and the carboxylic acid concentration in the polycarboxylic acid have a greater impact on the grafting process. Taking all factors into consideration, the sulfonium salt grafted antibacterial cotton fiber finally obtained by selecting the process conditions of Example 2 of the present invention and 25% malic acid\citric acid and 30% succinic acid\tartaric acid has the best comprehensive performance.

[0176] Because the grafting of the alkylsulfonium salt occurs only on the side chains of the cellulose macromolecule and does not disrupt the main cellulose chain, the key structural properties of the cotton fiber are preserved, with no significant changes in fiber morphology, structure, or mechanical properties. Furthermore, the positively charged sulfur in the grafted cellulose can adsorb negatively charged bacteria on the surface, while the long alkyl chains at the ends of the alkylsulfonium salt disrupt the permeability of bacterial cell membranes, leading to bacterial rupture and death, thus achieving antibacterial properties. Because the carboxyl groups are bound to the cellulose via newly formed ester bonds, and the carboxyl groups are bound to the alkylsulfonium salt via electrostatic adsorption, physical forces such as friction and washing are unlikely to disrupt the chemical bonds, resulting in long-term, stable, and effective antibacterial effects. Using the preparation method of the present invention, the fiber surface morphology remains unchanged before and after modification, exhibiting excellent antibacterial efficacy, washability, and long-lasting antibacterial properties. It also exhibits excellent biocompatibility and exhibits no significant toxic side effects. The fibers produced through esterification and electrostatic adsorption exhibit long-term, stable, contact-type antibacterial properties, excellent biosafety, and a simple, easy-to-use process suitable for mass production.

[0177] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Any changes, modifications, additions or substitutions made by ordinary technicians in this technical field within the essential scope of the present invention should fall within the scope of protection of the present invention.

Claims

1. A method for preparing a long-lasting antibacterial cotton fiber grafted with a sulfonium salt, characterized in that: The steps include:

1. Cotton fiber modification: (1) Mix polycarboxylic acid, sodium phosphate, disodium hydrogen phosphate, sodium hypophosphite and water to obtain a modified solution, which is then set aside; (2) Take a certain amount of cotton fiber and completely immerse and disperse it in the modified solution, and react it with magnetic stirring at 40-100℃ for 0.5-5h to obtain modified cotton fiber with carboxyl groups on the surface; 2. Preparation of alkyl sulfonium salts: (3) Add octadecyl sulfide and methyl iodide to N,N-dimethylformamide / water solution and react for 24-48 hours to obtain a solution; (4) The obtained solution was dialyzed in 0.1 mol / L sodium chloride solution for 24 h, and then dialyzed in deionized water for 24 h; (5) The dialyzed solution was freeze-dried for 48 h to obtain an alkyl sulfonium salt; 3. Sulfonium salt grafted cotton fiber: (6) Soak the modified cotton fiber obtained in step (2) in an alkaline aqueous solution, add the alkyl sulfonium salt obtained in step (5), and stir the reaction at 40-80°C for 1-4 hours; (7) Obtaining sulfonium salt grafted antibacterial cotton fiber; When the polycarboxylic acid is malic acid or citric acid, the mass ratio of cotton fiber, water, malic acid or citric acid, sodium phosphate, disodium hydrogen phosphate, and sodium hypophosphite is 6:100:20-25:0.5:0.8:5; when the polycarboxylic acid is succinic acid or tartaric acid, the mass ratio of cotton fiber, water, succinic acid or tartaric acid, sodium phosphate, disodium hydrogen phosphate, and sodium hypophosphite is 6:100:15-30:0.5:0.8:

5.

2. The method for preparing the long-lasting antibacterial cotton fiber grafted with sulfonium salt according to claim 1, wherein: In the step (2), the cotton fibers are reacted in the modified solution at 80° C. with magnetic stirring for 1 hour.

3. The method for preparing the long-lasting antibacterial cotton fiber grafted with sulfonium salt according to claim 1, wherein: In the step (3), the mass ratio of octadecyl sulfide to methyl iodide is 1:1-5, and the mass ratio of the N,N-dimethylformamide / water solution is 1:0.5-1.

5.

4. The method for preparing the long-lasting antibacterial cotton fiber grafted with sulfonium salt according to claim 1, wherein: In the step (6), the pH value of the alkaline aqueous solution is 9.5-10.5, and the mass ratio of the alkyl sulfonium salt, the cotton fiber, and the water is 0.5:6:

100.

5. The method for preparing the long-lasting antibacterial cotton fiber grafted with sulfonium salt according to claim 1, wherein: In the step (6), the modified cotton fiber is immersed in an alkaline aqueous solution and stirred at 50° C. for 3 hours.

6. The method for preparing the long-lasting antibacterial cotton fiber grafted with sulfonium salt according to claim 3, wherein: The mass ratio of the octadecyl sulfide to methyl iodide is 1:3, and the ratio of the N,N-dimethylformamide / water solution is 1:0.

8.

7. The method for preparing the long-lasting antibacterial cotton fiber grafted with sulfonium salt according to claim 4, characterized in that: In step (6), the pH value of the alkaline aqueous solution is 10.

8. A long-lasting antibacterial cotton fiber grafted with a sulfonium salt, characterized in that: Prepared by the preparation method according to any one of claims 1 to 7.

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