Antibacterial long-staple cotton towel and preparation process thereof

Abstract

This invention discloses a preparation process for antibacterial long-staple cotton towels, comprising: pre-treating long-staple cotton fibers with low-alkali scouring and oxygen bleaching; selectively oxidizing chitosan fibers to introduce aldehyde functional groups onto their surface, resulting in partially aldehyde-modified chitosan fibers; blending the partially aldehyde-modified chitosan fibers with the pre-treated long-staple cotton fibers and weaving them into towel fabric; after dyeing, finishing with a reactive antibacterial finishing agent containing free amino groups, whereby, under the action of a polycarboxylic acid crosslinking agent, the aldehyde groups on the surface of the oxidized chitosan fibers react with the amino groups in the finishing agent to form a Schiff base reaction, while the finishing agent and long-staple cotton fibers form a stable crosslinked structure; and then undergoing a reduction stabilization treatment to convert the Schiff base bonds into stable carbon-nitrogen single bonds. This invention achieves firm fixation of antibacterial components through a chemical anchoring mechanism, and the resulting towels maintain an antibacterial rate of no less than 95% after 50 standard washes, while also retaining good softness and absorbency.

Description

Technical Field

[0001] This invention relates to the field of cotton towels, and more particularly to an antibacterial long-staple cotton towel and its preparation process. Background Technology

[0002] Towels are indispensable daily textiles. Because towels are constantly damp and in frequent contact with human skin, they are highly susceptible to the growth and reproduction of bacteria, mold, and other microorganisms. This not only produces unpleasant odors and affects the user experience but can also lead to health problems such as skin allergies and infections. With rising living standards and increased health awareness, consumers are demanding higher levels of antibacterial and bacteriostatic properties from towels, making high-quality towels with long-lasting antibacterial properties increasingly popular. High-end towels made from long-staple cotton, in particular, occupy a significant market position due to their fine fibers, soft feel, and excellent absorbency, driven by the trend of consumption upgrading. How to imbue long-staple cotton towels with long-lasting antibacterial properties while maintaining their excellent feel has become a pressing technical challenge for the industry.

[0003] Currently, the main technical route for preparing antibacterial towels is the antibacterial finishing method. This involves impregnating, padding, or coating the finished towel with an antibacterial finishing agent, allowing the agent to adhere to the fiber surface and thus imparting antibacterial functionality. This method is relatively simple and low-cost, and is currently the most widely used antibacterial treatment method in industrial applications. The antibacterial finishing agents used mainly include silver-based inorganic antibacterial agents, quaternary ammonium salt organic antibacterial agents, and natural antibacterial agents such as chitosan and its derivatives. However, this method has a common problem: the antibacterial finishing agent mainly adheres to the fiber surface through physical adsorption, hydrogen bonding, or weak ionic bonding, lacking a strong chemical bond connection with the fiber. This causes the antibacterial layer to gradually detach and be lost under repeated washing, friction, and rubbing during daily use, resulting in poor antibacterial durability. After multiple standard washes, the antibacterial rate of the towel often decreases significantly, failing to meet consumers' demand for long-lasting antibacterial functionality.

[0004] Therefore, there is an urgent need to develop a preparation process that can fundamentally solve the above-mentioned technical bottlenecks, and on the basis of giving full play to the natural excellent hand feel characteristics of long-staple cotton fibers, achieve the chemical anchoring and stabilization of antibacterial components on the fiber surface, so that towel products have the comprehensive performance of highly efficient and long-lasting antibacterial, excellent wash fastness and soft and comfortable hand feel. Summary of the Invention

[0005] The present invention provides an antibacterial long-staple cotton towel and its preparation process, which is used to solve the related technical problems in the background art.

[0006] The technical solution provided by this invention is as follows: A preparation process for an antibacterial long-staple cotton towel includes the following steps: S1. Pre-treat long-staple cotton fibers by using low-alkali scouring and oxygen bleaching processes to remove impurities and natural waxes. S2. Selective oxidation treatment is performed on chitosan fibers to introduce aldehyde functional groups on the surface of chitosan fibers, resulting in partially aldehyde-modified chitosan fibers with aldehyde functional groups on the surface. S3. The partially aldehyde-modified chitosan fiber is blended with the pretreated long-staple cotton fiber to obtain a blended yarn, and the blended yarn is used to weave a towel fabric. S4. Dye the towel fabric; S5. The dyed towel fabric is treated with a reactive antibacterial finishing agent containing free amino groups, so that the aldehyde groups on the surface of the partially aldehyde-modified chitosan fibers react with the amino groups in the reactive antibacterial finishing agent in a Schiff base reaction. At the same time, the hydroxyl groups and / or amino groups in the reactive antibacterial finishing agent form a stable cross-linked structure with the hydroxyl groups on the surface of the long-staple cotton fibers under the action of a polycarboxylic acid cross-linking agent. S6. The product obtained in step S5 is subjected to reduction stabilization treatment to reduce the Schiff base bond to a stable carbon-nitrogen single bond. S7. After washing, softening and shaping, antibacterial long-staple cotton towels are obtained.

[0007] In one embodiment, in step S1, the sodium carbonate concentration in the low-alkali refining solution is 2-6 g / L, and the pH is adjusted to 8-9 using sodium carbonate.

[0008] In one embodiment, step S2, the selective oxidation treatment includes: placing chitosan fibers in a sodium periodate solution with a concentration of 0.05–0.15 g / mL, reacting under light-protected conditions for 4–12 h, and then washing and drying to obtain partially aldehyde-modified chitosan fibers with an aldehyde content of 0.2–0.8 mmol / g.

[0009] In one embodiment, in step S3, the partially aldehyde-modified chitosan fibers account for 8% to 12% of the total mass of the blended fibers.

[0010] In one embodiment, the blended yarn is produced using a compact Sirospun process.

[0011] In one embodiment, the reactive antibacterial finishing agent is a partially quaternized chitosan derivative.

[0012] In one embodiment, the finishing solution comprises: 10-25 g / L of partially quaternized chitosan derivative; 5-10 g / L of crosslinking agent; and 3-5 g / L of catalyst.

[0013] In one embodiment, the crosslinking agent includes malonic acid and citric acid.

[0014] In one embodiment, in step S6, the reduction stabilization treatment is performed using a sodium borohydride solution or a sodium cyanoborohydride solution.

[0015] The antibacterial long-staple cotton towel prepared by the above process has a partially aldehyde-modified chitosan fiber content of 8% to 12%, and a chemically cross-linked antibacterial layer is formed on the fiber surface, which is composed of partially aldehyde-modified chitosan fibers, reactive antibacterial finishing agents and polycarboxylic acid cross-linking agents.

[0016] Compared with the prior art, the beneficial effects of the present invention are: (1) The preparation process of the antibacterial long-staple cotton towel of the present invention adopts the selective oxidation treatment of chitosan fiber and low proportion blending with long-staple cotton fiber, combined with reactive antibacterial finishing and reduction stabilization treatment. By introducing active aldehyde groups on the surface of chitosan fiber, it can react chemically with the free amino groups in the antibacterial finishing agent. At the same time, under the action of polycarboxylic acid crosslinking agent, the antibacterial finishing agent is further promoted to form a stable crosslinking structure with the long-staple cotton fiber. The chemical bond stability is improved by reduction treatment, thereby achieving the purpose of improving the binding strength and wash resistance stability of antibacterial components on the surface of towel fiber. Thus, it achieves the technical effect of maintaining a high antibacterial rate, excellent wash resistance, good softness and water absorption even with a low chitosan fiber addition ratio. This solves the technical problems of existing antibacterial towels where a high proportion of antibacterial fiber blending leads to a decrease in hand feel, or the post-finishing antibacterial agent mainly relies on physical adsorption and is easily lost during washing, making it difficult to balance antibacterial durability and user comfort. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the preparation process of the present invention. Detailed Implementation

[0018] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0019] Example 1 This invention relates to a process for preparing antibacterial long-staple cotton towels, comprising the following steps: S1, Long-staple cotton fiber pretreatment Xinjiang long-staple cotton was selected as the base raw material, with an average fiber length of 37 mm and a fineness of 7600 metric count. First, the long-staple cotton fibers underwent opening and impurity removal treatment, followed by pretreatment in a scouring solution. The scouring solution contained 4 g / L sodium carbonate, 2 g / L scouring enzyme, and 1.5 g / L penetrant, with a controlled liquor ratio of 1:15, and treatment at 65℃ for 40 minutes to remove natural impurities and waxy components from the surface of the long-staple cotton fibers. Throughout this low-alkali scouring process, sodium carbonate was used to adjust the pH to 8-9 to avoid high-concentration strong alkali treatment. After scouring, bleaching was performed using an oxygen bleaching solution containing 5 g / L hydrogen peroxide and 2 g / L stabilizer, reacting at 95℃ for 45 minutes. After treatment, the fibers were washed with deionized water until neutral and dried at 80℃ for later use.

[0020] S2, Selective oxidation treatment of chitosan fibers Chitosan fibers with a length of 38 mm and a fineness of 1.7 dtex were selected and impregnated in a sodium periodate solution with a concentration of 0.10 g / mL at a bath ratio of 1:30. The reaction was carried out at 25 °C for 8 hours under light-protected conditions to selectively oxidize the chitosan fibers. After the reaction, the fibers were repeatedly washed with deionized water until no residual periodate ions were detected. Then, they were dried under vacuum at 50 °C for 4 hours to obtain partially aldehyde-modified chitosan fibers with an aldehyde content of 0.45 mmol / g.

[0021] S3, blended fabrics and weaving The aforementioned partially aldehyde-modified chitosan fibers were blended with pretreated long-staple cotton fibers at a mass ratio of 10:90. After carding, drawing, roving, and spinning processes, the blended yarn was spun into an 18.2 tex blended yarn using a compact Sirospun process, with a twist coefficient controlled at 335. The partially aldehyde-modified chitosan fibers accounted for 10% of the mass of this blended yarn. Subsequently, this blended yarn was used as terry yarn, and pure long-staple cotton yarn was used as the warp and weft yarns to weave terry cloth on a rapier towel loom.

[0022] S4, Staining treatment The resulting towel fabric was dyed with low-temperature reactive dyes at a temperature of 60℃ for 40 minutes. An acetate-sodium acetate buffer system was used to maintain the pH of the dye bath at 6.5 to minimize the damage to the aldehyde structure caused by the acidic or alkaline environment. After dyeing, the fabric was soaped, washed, and dried for later use.

[0023] S5, Reactive Antibacterial Finishing The finishing solution was prepared, comprising: 18 g / L of partially quaternized chitosan derivative (amino content 3.8 mmol / g), 4 g / L of citric acid, 4 g / L of malonic acid, 4 g / L of sodium hypophosphite, and 6 g / L of softener. The towel fabric was finished using a two-dip, two-nip process, with the nip-in solution ratio controlled at 80%. It was then pre-dried at 85°C for 3 minutes, followed by baking at 140°C for 4 minutes. During the baking process, the aldehyde groups (-CHO) on the surface of oxidized chitosan fibers undergo a Schiff base reaction with the free amino groups (-NH2) in some quaternized chitosan derivatives to generate a Schiff base structure containing carbon-nitrogen double bonds (-C=N-). At the same time, under the action of malonic acid and citric acid composite crosslinking agents, the hydroxyl groups in some quaternized chitosan derivatives undergo an esterification crosslinking reaction with the hydroxyl groups on the surface of long-staple cotton fibers. Meanwhile, their free amino groups participate in the construction of the crosslinking network, forming a stable multi-point chemical fixation structure, thereby constructing an interpenetrating crosslinking network containing Schiff base bonds and ester bonds on the fiber surface.

[0024] S6, Restoration Stabilization Process After baking, the towel is placed in a 0.05 mol / L sodium borohydride solution and treated at 25°C for 30 minutes to further reduce the Schiff base bond (-C=N-) to a more stable carbon-nitrogen single bond (-CN-), thereby improving the chemical stability and wash fastness of the antibacterial finishing layer.

[0025] S7, Post-processing and Finished Products After the reduction and stabilization treatment is completed, the residual reagents are removed by washing with water, followed by softening and stretching at 110°C to obtain the antibacterial long-staple cotton towel product of this embodiment.

[0026] Example 2 The difference between this embodiment and Example 1 is that: chitosan fibers were impregnated in a sodium periodate solution with a concentration of 0.15 g / mL and reacted at 25°C for 4 hours under light-protected conditions. After the reaction was completed, the fibers were washed and dried to obtain partially aldehyde-modified chitosan fibers with an aldehyde content of 0.68 mmol / g. Subsequently, this partially aldehyde-modified chitosan fiber was blended with long-staple cotton fiber at a mass ratio of 8:92 and prepared according to the spinning, weaving, dyeing, antibacterial finishing, reduction stabilization treatment, and post-finishing processes described in Example 1 to finally obtain an antibacterial long-staple cotton towel.

[0027] Example 3 The difference between this embodiment and Example 1 is that chitosan fibers were impregnated in a sodium periodate solution with a concentration of 0.05 g / mL and reacted at 25°C for 12 hours under light-protected conditions. After treatment, partially aldehyde-modified chitosan fibers with an aldehyde content of 0.25 mmol / g were obtained. Subsequently, this partially aldehyde-modified chitosan fiber was blended with long-staple cotton fibers at a mass ratio of 12:88. In the subsequent antibacterial finishing process, the amount of quaternized chitosan derivatives was increased to 22 g / L, while the remaining process parameters remained the same as in Example 1, ultimately yielding an antibacterial long-staple cotton towel.

[0028] Comparative Example 1 This comparative example is essentially the same as Example 1, except that the chitosan fibers were not subjected to sodium periodate oxidation treatment; instead, ordinary chitosan fibers and long-staple cotton fibers were directly blended at a mass ratio of 30:70. No sodium borohydride reduction stabilization treatment was performed after finishing. The remaining process steps are consistent with Example 1. This comparative example is used to simulate the simple physical superposition of "antibacterial fiber blending and antibacterial finishing" in the prior art, and to verify the synergistic effect of chitosan fiber oxidation treatment and reduction stabilization treatment on antibacterial and wash-resistant properties in this invention.

[0029] Performance testing The towel products obtained in Examples 1-3 and Comparative Example 1 were subjected to performance tests according to the following standards and methods: Antibacterial rate test: Referring to GB / T 20944.3-2008 "Evaluation of antibacterial properties of textiles - Part 3: Shaking method", Staphylococcus aureus (ATCC 6538) was selected as the test species, and the antibacterial rate was tested before washing and after 50 standard washes. The standard washing method was in accordance with GB / T 8629-2017, using a type A washing machine, washing program 4N, water temperature 40℃, and ECE standard detergent. After each washing cycle, the clothes were hung to dry, for a total of 50 cycles.

[0030] Hand feel evaluation: Five trained professional evaluators were invited to conduct a blind evaluation to comprehensively score the softness, fluffiness and smoothness of the towel samples, with a maximum score of 5 points (the higher the score, the better the hand feel), and the average score was taken as the hand feel score result.

[0031] Water absorption time test: Refer to the test method for water absorption in GB / T 22799-2019 "Towels" and use the vertical sinking method to record the time required for the sample to go from contact with the water surface to complete immersion.

[0032] Hair removal rate test: The test was conducted in accordance with FZ / T 60029-2021 "Test Method for Hair Removal Rate of Towel Products".

[0033] The test results are shown in the table below: The test results above show that: Comparison of Examples 1-3 with Comparative Example 1: In the examples of this invention, using only 8%–12% chitosan fiber blending, the antibacterial rate remained above 96.5% after 50 standard washes, with a decrease of only 2.6%–3.2%. In contrast, Comparative Example 1 (chitosan fiber without oxidation or reduction stabilization treatment), although also using a blending and finishing process, showed a significant decrease in antibacterial rate to 81.5% after 50 washes, a decrease of 17.8%. This difference clearly demonstrates that the selective oxidation treatment of chitosan fiber introduces active aldehyde groups, enabling it to react with the amino groups of the antibacterial finishing agent during the baking stage to form covalent bonds through a Schiff base reaction. The subsequent sodium borohydride reduction treatment further converts the reversible Schiff base bond (-C=N-) into an irreversible stable carbon-nitrogen single bond (-CN-), significantly improving the chemical stability of the antibacterial layer during repeated washing. Due to the lack of this chemical anchoring and stabilization mechanism, the antibacterial finishing agent in Comparative Example 1 only relies on physical adsorption and weak ionic bonding to adhere to the fiber surface, and is easily lost during washing, resulting in antibacterial durability that is far inferior to the technical solution of this invention.

[0034] The present invention provides a preparation process for an antibacterial long-staple cotton towel. First, chitosan fibers are selectively oxidized to introduce active aldehyde groups on the surface of the chitosan fibers. Then, the chitosan fibers are blended with long-staple cotton fibers in a low proportion, so that the chitosan fibers can be evenly dispersed inside the towel fiber system. While ensuring the existence of the basic carrier for antibacterial function, the process avoids the problems of decreased spinning performance, fabric stiffness, and poor water absorption caused by traditional high-proportion chitosan blending. Thus, basic antibacterial function is achieved while maintaining the soft and skin-friendly properties of long-staple cotton.

[0035] Furthermore, after the towel fabric is dyed, the present invention uses a reactive antibacterial finishing agent containing free amino groups for finishing. This causes the aldehyde groups on the surface of the oxidized chitosan fiber to react with the amino groups in the antibacterial finishing agent in a Schiff base reaction. At the same time, under the action of the polycarboxylic acid crosslinking agent, the antibacterial finishing agent is further promoted to form a stable crosslinking structure with the long-staple cotton fiber. This results in the antibacterial components forming a multi-point chemical fixation structure with the chitosan fiber and the long-staple cotton fiber, respectively. This significantly improves the binding strength of the antibacterial finishing agent on the fiber surface and effectively solves the problem that the antibacterial components in the traditional antibacterial finishing process mainly rely on physical adsorption and are easily lost during repeated washing.

[0036] Furthermore, the present invention includes a reduction stabilization step, which reduces the initially formed Schiff base bonds to a more stable carbon-nitrogen single bond structure, further improving the hydrolysis resistance and wash stability of the antibacterial functional layer, so that the product can maintain high antibacterial activity after multiple washes.

[0037] Performance tests show that the antibacterial long-staple cotton towel produced by this invention achieves an antibacterial rate of over 99% before washing, and maintains an antibacterial rate of over 95% after 50 standard washes. Compared to the comparative product that has not undergone oxidation and stabilization treatment, its antibacterial durability is significantly improved. At the same time, the product of this invention maintains good softness, absorbency, and a low lint rate, thus balancing antibacterial performance with user comfort.

[0038] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing the invention and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0039] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A manufacturing process for an antibacterial long-staple cotton towel, characterized in that, Includes the following steps: S1. Pre-treat long-staple cotton fibers by using low-alkali scouring and oxygen bleaching processes to remove impurities and natural waxes. S2. Selective oxidation treatment is performed on chitosan fibers to introduce aldehyde functional groups on the surface of chitosan fibers, resulting in partially aldehyde-modified chitosan fibers with aldehyde functional groups on the surface. S3. The partially aldehyde-modified chitosan fiber is blended with the pretreated long-staple cotton fiber to obtain a blended yarn, and the blended yarn is used to weave a towel fabric. S4. Dye the towel fabric; S5. The dyed towel fabric is treated with a reactive antibacterial finishing agent containing free amino groups, so that the aldehyde groups on the surface of the partially aldehyde-modified chitosan fibers react with the amino groups in the reactive antibacterial finishing agent in a Schiff base reaction. At the same time, the hydroxyl groups and / or amino groups in the reactive antibacterial finishing agent form a stable cross-linked structure with the hydroxyl groups on the surface of the long-staple cotton fibers under the action of a polycarboxylic acid cross-linking agent. S6. The product obtained in step S5 is subjected to reduction stabilization treatment to reduce the Schiff base bond to a stable carbon-nitrogen single bond. S7. After washing, softening and shaping, antibacterial long-staple cotton towels are obtained.

2. The preparation process of an antibacterial long-staple cotton towel according to claim 1, characterized in that, In step S1, the sodium carbonate concentration in the low-alkali refining solution is 2-6 g / L, and the pH is adjusted to 8-9 using sodium carbonate.

3. The preparation process of an antibacterial long-staple cotton towel according to claim 1, characterized in that, In step S2, the selective oxidation treatment includes: placing chitosan fibers in a sodium periodate solution with a concentration of 0.05–0.15 g / mL, reacting under light-protected conditions for 4–12 h, and then washing and drying to obtain partially aldehyde-modified chitosan fibers with an aldehyde content of 0.2–0.8 mmol / g.

4. The preparation process of an antibacterial long-staple cotton towel according to claim 1, characterized in that, In step S3, the partially aldehyde-modified chitosan fibers account for 8% to 12% of the total mass of the blended fibers.

5. The preparation process of an antibacterial long-staple cotton towel according to claim 1, characterized in that, The blended fabric is produced using a compact Sirospun process.

6. The preparation process of an antibacterial long-staple cotton towel according to claim 1, characterized in that, The reactive antibacterial finishing agent is a partially quaternized chitosan derivative.

7. The preparation process of an antibacterial long-staple cotton towel according to claim 6, characterized in that, The finishing solution includes: 10-25 g / L of partially quaternized chitosan derivatives; 5-10 g / L of crosslinking agent; and 3-5 g / L of catalyst.

8. The preparation process of an antibacterial long-staple cotton towel according to claim 7, characterized in that, The crosslinking agents include malonic acid and citric acid.

9. The preparation process of an antibacterial long-staple cotton towel according to claim 1, characterized in that, In step S6, the reduction stabilization treatment is carried out using sodium borohydride solution or sodium cyanoborohydride solution.

10. The antibacterial long-staple cotton towel prepared by the process according to any one of claims 1 to 9, characterized in that, The towel contains 8% to 12% partially aldehyde-modified chitosan fibers, and a chemically cross-linked antibacterial layer is formed on the fiber surface, consisting of partially aldehyde-modified chitosan fibers, reactive antibacterial finishing agents, and polycarboxylic acid cross-linking agents.

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