Preparation process of antibacterial fabric based on polydimethylsiloxane-nano silver composite system

Abstract

This invention relates to the field of textile fabric technology, and in particular to a preparation process of an antibacterial fabric based on a polydimethylsiloxane-nano silver composite system, comprising the following steps: (1) Pretreatment: The fabric is treated with alkali reduction to obtain the treated fabric for later use; (2) Dyeing and antibacterial finishing: The fabric prepared in step (1) is immersed in a dyeing solution with a bath ratio of 1:20-30; the pH of the dyeing solution is first adjusted to 50-5.5 and kept at 65-80℃ for 40-60 min; then the temperature is increased to 105℃-110℃ at a rate of 1-1.5℃ / min and kept at 105℃-110℃ for 30-45 min; after dyeing, the temperature is lowered to 65-80℃ to obtain the dyed fabric for later use; the dyeing solution contains a polydimethylsiloxane / nano silver composite dispersion; (3) Posttreatment: The dyed fabric in step (2) is subjected to soaping, washing, and setting to obtain the antibacterial fabric. The above process can obtain a highly efficient, durable, and safe antibacterial fabric.

Description

Technical Field

[0001] This invention relates to the field of textile fabric technology, and in particular to a preparation process for an antibacterial fabric based on a polydimethylsiloxane-nano silver composite system. Background Technology

[0002] Currently, there are various methods for preparing antibacterial fabrics on the market, among which finishing with antibacterial auxiliaries is a common approach. Nano-silver (AgNPs) is widely used in the development of antibacterial textiles due to its broad-spectrum antibacterial properties and low tendency to induce drug resistance. However, directly loading nano-silver onto the fabric surface presents the following problems: nano-silver binds to fibers primarily through physical adsorption or ion exchange, lacking strong chemical bonds, and is easily detached under the mechanical forces of washing, leading to a rapid decline in antibacterial performance. To address the issue of nano-silver detachment, some studies have attempted to use polymeric adhesives to fix nano-silver onto the fiber surface. For example, polymers such as polyurethane, polyacrylate, and chitosan are physically blended with nano-silver and then applied to the fabric through padding or coating processes. However, the bonding between these polymers and nano-silver mainly relies on non-covalent interactions such as van der Waals forces or hydrogen bonds, resulting in relatively weak adhesion. Furthermore, the adhesive film may affect the fabric's hand feel, breathability, and hydrophilicity. Therefore, existing physical blending methods have not fundamentally solved the problem of poor wash resistance of nano-silver. Polydimethylsiloxane (PDMS) is an organosilicon polymer with low surface energy, good flexibility and biocompatibility. It has been widely used for waterproofing and softening fabrics and can form a continuous film on the fiber surface.

[0003] Although polydimethylsiloxane (PDMS) has been used in fabric finishing and silver nanoparticles (AgNPs) have been widely used for antibacterial purposes, current technologies typically use them as a physical blend, resulting in a lack of strong chemical bonds and poor wash resistance. Currently, there are no publicly reported technical solutions that simultaneously use PDMS as a "covalent anchoring agent" and "ion-release isolation layer" for silver nanoparticles. Furthermore, there is a lack of practical experience in applying chemically bonded PDMS-Ag composite systems to the high-temperature, high-pressure dyeing and finishing process of polyester fibers. How to anchor PDMS to the surface of AgNPs through chemical bonds and utilize the film-forming behavior of PDMS on the fiber surface to achieve a firm loading and controlled release of silver nanoparticles remains a pressing technical challenge in this field. In conclusion, developing a method for preparing antibacterial fabrics that can achieve a firm bond between silver nanoparticles and fibers while simultaneously ensuring antibacterial durability and biosafety remains of significant practical importance. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a preparation process for antibacterial fabric based on polydimethylsiloxane-nano silver composite system, which can be used to obtain antibacterial fabric with good antibacterial effect, in order to overcome the shortcomings of the prior art.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0006] A process for preparing an antibacterial fabric based on a polydimethylsiloxane-silver nanocomposite system, wherein the fabric is a polyester fiber fabric, includes the following process steps:

[0007] (1) Pretreatment: Reduce the amount of alkali on the fabric to obtain the treated fabric for later use;

[0008] (2) Dyeing and antibacterial finishing: Immerse the fabric prepared in step (1) into the dyeing solution, and control the bath ratio to 1:20-30; first adjust the pH of the dyeing solution to 5.0-5.5, and keep it at 65-80℃ for 40-60 min; then raise the temperature to 105℃-110℃ at a rate of 1-1.5℃ / min, keep it at 105℃-110℃ for 30-45 min, and after dyeing, cool it down to 65-80℃ to obtain the dyed fabric for use; the dyeing solution contains polydimethylsiloxane / nano silver composite dispersion;

[0009] (3) Post-processing: The dyed fabric in step (2) is soaped, washed with water and set to obtain antibacterial fabric.

[0010] As an improved technical solution, in step (1), the concentration of caustic soda is 10-15 g / L, the bath ratio is 1:30-40, the treatment temperature is 95-100℃, and the treatment time is 20-30 min.

[0011] As an improved technical solution, the dyeing solution in step (2) includes 1-5% owf of disperse dye, 1-5% owf of polydimethylsiloxane / nano silver composite dispersion, 1-2 g / L of dispersant, and 0.5-1 g / L of leveling agent.

[0012] As an improved technical solution, the preparation process of the polydimethylsiloxane / nano silver composite dispersion in step (2) includes the following steps:

[0013] ① Hydroxyl-terminated polydimethylsiloxane and succinic anhydride are mixed in a molar ratio of 1:2.5, toluene and catalyst are added, and the mixture is refluxed for 4-5 hours under nitrogen protection. The solvent is removed by rotary evaporation, and the crude product is reconstituted, extracted and dried to obtain PDMS-COOH.

[0014] ② Take the PDMS-COOH mentioned in step ①, add an organic solvent and stir to dissolve, add a hydrochloric acid solution of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and an N-hydroxysuccinimide solution, stir and react for a period of time, remove the organic solvent by rotary evaporation, then re-dissolve, wash and dry to obtain a solution containing PDMS-COO-NHS.

[0015] ③ Take 80 mL of pure water, heat it to 92-100℃, add 1.3 mL of 1% (w / v) AgNO3 solution while stirring, then add 10 mL of 1% (w / v) sodium citrate solution, keep the temperature for 15-25 min, wait for the solution color to change from colorless to yellow and then to brownish-yellow, cool to room temperature, centrifuge and purify to obtain AgNPs dispersion;

[0016] ④ Take the AgNPs dispersion from step ③ and add cysteine ​​solution prepared with PBS buffer dropwise under nitrogen protection and stirring at room temperature to obtain a solution containing aminated AgNPs.

[0017] ⑤ Take the aminated AgNPs solution from step ④, concentrate it by centrifugation and ultrafiltration, and replace it with pH 6.0 MES buffer containing 0.1M NaCl to obtain an aminated AgNPs dispersion in the buffer. Under stirring and temperature control, slowly add the PDMS-COO-NHS solution from step ② to the above dispersion for reaction. After the reaction is complete, add the dispersant PVP K30 and continue stirring. Then, the reaction solution is centrifuged and ultrafiltered. The collected retentate is repeatedly washed and purified with PBS buffer containing 0.1% PVP K30. The obtained retentate is the polydimethylsiloxane / nano silver composite dispersion.

[0018] As an improved technical solution, the molar ratio of COOH in PDMS-COOH to 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide in step ② is 1:2:1.

[0019] As an improved technical solution, the concentration of cysteamine solution in step ④ is 50-100 mM.

[0020] As an improved technical solution, in step ⑤, the mass ratio of PDMS-COO-NHS in the solution containing PDMS-COO-NHS to the silver core in the aminated AgNPs in the solution containing aminated AgNPs is 20-25:1.

[0021] After adopting the above technical solution, the beneficial effects of the present invention are:

[0022] This invention fully utilizes the triple functions of polydimethylsiloxane by constructing a polydimethylsiloxane / silver nanocomposite system:

[0023] First, the anchoring and encapsulation effects: Under dyeing conditions of 100-108℃, polydimethylsiloxane molecular chains can spread on the surface of polyester fibers and form a continuous film, uniformly encapsulating and firmly anchoring the silver nanoparticles to the fiber surface. The segment entanglement, intermolecular hydrogen bonds, and dipole interactions between the polydimethylsiloxane molecular chains and polyester macromolecules, as well as the physical embedding effect after polydimethylsiloxane film formation, significantly improve the adhesion strength of the silver nanoparticles to the fiber surface.

[0024] Secondly, the dual function of anchoring and sustained release: the semi-permeable membrane structure formed by polydimethylsiloxane on the fiber surface, on the one hand, firmly anchors the silver nanoparticles through covalent bonds, effectively suppressing the risk of silver nanoparticles falling off due to mechanical washing; on the other hand, this semi-permeable membrane allows for the slow and continuous release of silver ions, thus ensuring long-lasting antibacterial activity. This design achieves the beneficial effect of "anchoring without sealing, and sustained release rather than burst release".

[0025] Third, the dispersing effect: The introduction of polydimethylsiloxane improves the dispersion stability of nano-silver in the dye bath, enabling it to be uniformly loaded onto the fiber surface during the dyeing process, thus ensuring the uniformity of the antibacterial effect. Through the synergistic effect of the above three actions, this invention achieves both high efficiency and long-lasting antibacterial properties. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0027] Example 1

[0028] A process for preparing an antibacterial fabric based on a polydimethylsiloxane-silver nanocomposite system includes the following steps:

[0029] (1) Pretreatment: The fabric (polyester fabric - 100% polyester fiber, 180gsm) was treated with caustic soda at a concentration of 10g / L, at a bath ratio of 1:30, at a temperature of 95℃ for 30 minutes and then the fabric was put into use.

[0030] (2) Dyeing and antibacterial finishing: Immerse the fabric prepared in step (1) in the dyeing solution (including 1% owf of disperse dye, 1% owf of polydimethylsiloxane / nano silver composite dispersion (based on the dry weight of PDMS-Ag composite, 1 gram of PDMS-Ag composite dry weight per 100 grams of fabric), 1 g / L of dispersant, and 0.5 g / L of leveling agent), control the bath ratio to 1:20, first adjust the pH of the dyeing solution to 5.0 with citric acid-sodium citrate buffer, and keep it at 65℃ for 40 min (so that the polydimethylsiloxane / nano silver composite dispersion is fully adsorbed on the fiber surface), then raise the temperature to 105℃ at a rate of 1℃ / min (under closed pressure conditions), keep it at 65℃ for 30 min, and then lower the temperature to 65℃ to obtain the dyed fabric for use.

[0031] The preparation process of the polydimethylsiloxane / nano silver composite dispersion includes the following steps:

[0032] ① Take 80g of hydroxyl-terminated polydimethylsiloxane (PDMS-OH, with a double-terminated hydroxyl structure, number-average molecular weight of 1500 Da ± 10%, molecular weight distribution ≤ 1.5, and hydroxyl value of 70-80 mg. Dissolve PDMS-COOH (PDMS-OH / g) completely in a 500mL three-necked flask by adding 200mL of anhydrous toluene. Add 13.3g of succinic anhydride (molar ratio of PDMS-OH:succinic anhydride = 1:2.5), 0.16g of 4-dimethylaminopyridine (DMAP, accounting for 0.2% of the mass of PDMS-OH), and 4.5mL of triethylamine. Heat to 110℃ and reflux for 4h under nitrogen protection. After the reaction, remove the solvent by rotary evaporation. Redissolve the crude product in 50mL of anhydrous toluene, then add it dropwise to 300mL of methanol in an ice bath with stirring. Allow the mixture to stand and separate into layers, then remove the supernatant. Repeat the precipitation and purification process twice, and then dry to constant weight to obtain a colorless, transparent, viscous PDMS-COOH. Infrared spectroscopy results show that the product is soluble in 1710cm⁻¹. -1 The presence of a characteristic absorption peak at the C=O stretching vibration of the carboxyl group, combined with acid-base titration detection (the measured carboxyl content was 1.18 mmol / g), confirmed the successful preparation of PDMS-COOH with a double-ended carboxyl group structure.

[0033] ② Take 1.35 g of PDMS-COOH from step ① (titrated to contain 1.6 mmol COOH), dissolve it in 20 mL of anhydrous THF, and stir until completely dissolved; add 613 mg (3.2 mmol) of EDC·HCl and 184 mg (1.6 mmol) of NHS, and slowly add about 100 μL of triethylamine to adjust the system to weakly alkaline; stir the reaction at room temperature in the dark for 4 h; after the reaction is completed, concentrate the THF by rotary evaporation under reduced pressure in a 40 °C water bath, then reconstitute the residue with DCM, wash with dilute hydrochloric acid, and after separation, collect the organic phase, dry it with anhydrous sodium sulfate, filter it, and concentrate it by rotary evaporation (to remove DCM) to obtain activated PDMS-COO-NHS; before use, dilute to volume with anhydrous THF to prepare a stock solution of 20 mg / mL;

[0034] ③ Take 80 mL of pure water, heat it to 95 °C, and add 1.3 mL of 1% (w / v) AgNO3 solution while stirring. Then add 10 mL of 1% (w / v) sodium citrate solution and keep it warm for 15 min. When the solution color changes from colorless to yellow and then to brownish-yellow, cool it to room temperature and centrifuge (centrifuge at 8000 rpm for 15 min at 4 °C). After removing the supernatant, add a buffer solution of pH 8.0 (1 mM sodium citrate solution) to resuspend it. Use vortexing to disperse the precipitate, continue centrifugation to remove the supernatant, add buffer solution to resuspend the precipitate, and make up to 32 mL to obtain a concentrated and purified AgNPs dispersion (the mass concentration of silver in the AgNPs dispersion is 0.21 mg / mL).

[0035] ④ Take 20 mL of the AgNPs dispersion from step ③, adjust the pH to 8.3 with 0.1 M NaOH solution, and determine the total amount of silver atoms in the dispersion by ICP-OES. Calculate the amount of cysteine ​​to be used based on a cysteine ​​to silver atom molar ratio of 3:1. Under nitrogen protection, prepare a 50 mM solution of the calculated amount of cysteine ​​with PBS buffer, and slowly add it dropwise to the AgNPs dispersion at a rate of 0.5 mL / min. React at room temperature for 2 h. After the reaction is complete, transfer the reaction solution to an ultrafiltration tube with a molecular weight cutoff of 10 kDa, and centrifuge at 4℃ and 4000 rpm for ultrafiltration. After concentrating to 1 / 3 of the original volume, add PBS buffer to replenish the original volume, and repeat the washing process 3 times. Collect the retentate and make up to 32 mL with PBS buffer to obtain the aminated AgNPs dispersion.

[0036] ⑤ Take 32 mL of the solution containing aminated AgNPs from step ④. The total mass of silver nuclei was determined to be 4.2 mg by ICP-OES. Transfer the dispersion to a 100 kDa ultrafiltration tube and centrifuge at 4000 rpm at 4℃ to concentrate to 5 mL. Then, add MES buffer (containing 0.1 M NaCl) at pH 6.0 to bring the total volume to 32 mL (repeat this concentration-displacement operation once to completely remove the original buffer system). Transfer the concentrated AgNPs dispersion to a reaction flask and place it in a constant temperature circulating water bath at 13℃ with magnetic stirring (500 rpm). Take 4.2 mL of the PDMS-COO-NHS stock solution (20 mg / mL) prepared in step ② (the required PDMS-COO-NHS mass is 84 mg, calculated based on a PDMS-COO-NHS to silver core mass ratio of 20:1). Slowly add this solution dropwise to the AgNPs dispersion at a rate of 0.1 mL / min. After the addition is complete, stir the mixture at 13°C for 1.5 h to complete the reaction. Then add PVPK30 (8.4 mg) at twice the mass of AgNPs and continue stirring for 30 min. Transfer the reaction solution to a 100 kDa ultrafiltration tube and centrifuge at 4°C and 4000 rpm for ultrafiltration. After concentrating to 1 / 5 of the original volume, add PBS buffer containing 0.1% PVPK30 to replenish the original volume. Repeat the washing process twice to remove excess unreacted PDMS-COO-NHS. The retentate was collected, diluted to 13 mL, and ultrasonically dispersed for 5 min to obtain a polydimethylsiloxane / silver nanocomposite dispersion. The silver content in the dispersion was determined to be 0.27 mg / mL by ICP-OES. The zeta potential of the dispersion was -24.5 mV, and the average particle size was 75 nm and the polydispersity index (PDI) was 0.13, as determined by dynamic light scattering.

[0037] (3) Post-treatment: Immerse the dyed fabric from step (2) in a solution containing 1 g / L of nonionic soaping agent (such as fatty alcohol polyoxyethylene ether) at a liquor ratio of 1:20. Treat at 50°C for 10 min. After soaping, wash with 40°C warm water for 10 min, then wash with room temperature cold water for 5 min. Finally, heat setting treatment is performed (using a pin plate tenter frame, setting temperature of 110°C, setting time of 75 seconds, overfeed rate of 1.5%, and width set to 102% of the original width). After setting, allow it to cool naturally to room temperature to obtain the antibacterial fabric.

[0038] Example 2

[0039] A process for preparing an antibacterial fabric based on a polydimethylsiloxane-silver nanocomposite system includes the following steps:

[0040] (1) Pretreatment: The fabric (polyester fabric - 100% polyester fiber, 180gsm) was treated with caustic soda at a concentration of 15g / L, at a bath ratio of 1:35, at a temperature of 98℃ for 25 minutes and then the fabric was put into use.

[0041] (2) Dyeing and antibacterial finishing: Immerse the fabric prepared in step (1) into the dyeing solution, which includes 2.5% owf of disperse dye, 3% owf of polydimethylsiloxane / nano silver composite dispersion (based on the dry weight of PDMS-Ag composite), 1.5 g / L of dispersant, and 0.8 g / L of leveling agent. Control the bath ratio to 1:25. First, adjust the pH of the dyeing solution to 5.2 with citrate-sodium citrate buffer, and keep it at 73℃ for 50 min (so that the polydimethylsiloxane / nano silver composite dispersion is fully adsorbed on the fiber surface). Increase the temperature to 108℃ at a rate of 1.2℃ / min (under closed pressure conditions), keep it at 70℃ for 40 min, and then cool it down to 70℃. The dyed fabric is ready for use.

[0042] The preparation process of the polydimethylsiloxane / nano silver composite dispersion includes the following steps:

[0043] ① Take 80g of hydroxyl-terminated polydimethylsiloxane (PDMS-OH, with a double-terminated hydroxyl structure, number-average molecular weight of 1500 Da ± 10%, molecular weight distribution ≤ 1.5, and hydroxyl value of 70-80 mg. Dissolve PDMS-COOH (PDMS-OH / g) completely in a 500mL three-necked flask by adding 200mL of anhydrous toluene. Add 13.3g of succinic anhydride (molar ratio of PDMS-OH:succinic anhydride = 1:2.5), 0.16g of 4-dimethylaminopyridine (DMAP, accounting for 0.2% of the mass of PDMS-OH), and 4.5mL of triethylamine. Reflux at 110℃ for 4.5h under nitrogen protection. After the reaction, remove the solvent by rotary evaporation. Redissolve the crude product in 50mL of anhydrous toluene, then add it dropwise to 300mL of methanol in an ice bath with stirring. Allow the mixture to stand and separate into layers, then remove the supernatant. Repeat the precipitation and purification process twice, then dry to constant weight to obtain a colorless, transparent, viscous PDMS-COOH. Infrared spectroscopy results show that the product is soluble in 1710cm⁻¹. -1 The presence of a characteristic absorption peak at the C=O stretching vibration of the carboxyl group, combined with acid-base titration detection (the measured carboxyl content was 1.20 mmol / g), confirmed the successful preparation of PDMS-COOH with a double-ended carboxyl group structure.

[0044] ② Take 1.35 g of PDMS-COOH from step ① (titrated to contain 1.6 mmol COOH), dissolve it in 20 mL of anhydrous THF, and stir until completely dissolved; add 613 mg (3.2 mmol) of EDC·HCl and 184 mg (1.6 mmol) of NHS, and slowly add about 100 μL of triethylamine to adjust the system to weakly alkaline; stir the reaction at room temperature in the dark for 4 h; after the reaction is completed, concentrate the THF by rotary evaporation under reduced pressure in a 40 °C water bath, then reconstitute the residue with DCM, wash with dilute hydrochloric acid, and after separation, collect the organic phase, dry it with anhydrous sodium sulfate, filter it, and concentrate it by rotary evaporation (to remove DCM) to obtain activated PDMS-COO-NHS; before use, dilute to volume with anhydrous THF to prepare a stock solution of 20 mg / mL;

[0045] AgNPs particle size characterization: An appropriate amount of the above AgNPs dispersion was dropped onto a copper grid of a carbon support film. After drying, the particle size was observed using a transmission electron microscope (TEM, JEOL JEM-2100F, 200 kV). At least 200 particles were randomly measured, and the average particle size, particle size distribution range, and polydispersity index (PDI) of the AgNPs were statistically obtained. The specific surface area of ​​spherical particles was calculated using the formula S = 6 / (ρ·d) (where ρ is the density of silver, 10.49 g / cm³). 3 The specific surface area of ​​AgNPs was calculated by taking d as the average particle size. A summary of the particle size and specific surface area of ​​AgNPs in each embodiment is shown in Table 1.

[0046]

[0047] ③ Take 80 mL of pure water, heat it to 96 °C, and add 1.3 mL of 1% (w / v) AgNO3 solution while stirring. Then add 10 mL of 1% (w / v) sodium citrate solution and keep it warm for 20 min. When the solution color changes from colorless to yellow and then to brownish-yellow, cool it to room temperature and centrifuge (centrifuge at 9000 rpm for 18 min at 4 °C). Remove the supernatant and resuspend it in pH 8.3 buffer (1 mM sodium citrate solution). Vortex the precipitate to redisperse it. Continue to centrifuge to remove the supernatant, and then add buffer to resuspend the precipitate. Make up the volume to 32 mL to obtain the concentrated and purified AgNPs dispersion (the mass concentration of silver in the AgNPs dispersion is 0.22 mg / mL).

[0048] ④ Take 20 mL of the AgNPs dispersion from step ③, adjust the pH to 8.5 with 0.1 M NaOH solution, and determine the total amount of silver atoms in the dispersion by ICP-OES. Calculate the amount of cysteine ​​to be used based on a cysteine ​​to silver atom molar ratio of 2.5:1. Under nitrogen protection, prepare an 80 mM solution of the calculated amount of cysteine ​​with PBS buffer, and slowly add it dropwise to the AgNPs dispersion at a rate of 0.8 mL / min. React at room temperature for 3 h. After the reaction is complete, transfer the reaction solution to an ultrafiltration tube with a molecular weight cutoff of 10 kDa, and centrifuge at 4℃ and 4000 rpm for ultrafiltration. After concentrating to 1 / 3 of the original volume, add PBS buffer to replenish the original volume, and repeat the washing process 3 times. Collect the retentate and make up to 32 mL with PBS buffer to obtain the aminated AgNPs dispersion.

[0049] ⑤ Take 32 mL of the solution containing aminated AgNPs from step ④. The total mass of silver nuclei was determined to be 4.4 mg by ICP-OES. Transfer the dispersion to a 100 kDa ultrafiltration tube and centrifuge at 4000 rpm at 4℃ to concentrate to 5 mL. Then, add MES buffer (containing 0.1 M NaCl) at pH 6.0 to bring the total volume to 32 mL (repeat this concentration-displacement operation once to completely remove the original buffer system). Transfer the concentrated AgNPs dispersion to a reaction flask and place it in a constant temperature circulating water bath at 18℃ with magnetic stirring (600 rpm). Take 5.5 mL of the PDMS-COO-NHS (20 mg / mL) stock solution from step ② (the required PDMS-COO-NHS mass is calculated to be 110 mg based on a PDMS-COO-NHS to silver core mass ratio of 25:1). Slowly add this solution dropwise to the AgNPs dispersion at a rate of 0.3 mL / min. After the addition is complete, stir the mixture at 18°C ​​for 1 h to complete the reaction. Then add 2 times the mass of AgNPs (based on silver element) of PVP K30 (i.e., 8.8 mg) and continue stirring for 30 min. Transfer the reaction solution to a 100 kDa ultrafiltration tube and centrifuge at 4°C and 4000 rpm for ultrafiltration. After concentrating to 1 / 5 of the original volume, add PBS buffer containing 0.1% PVP K30 to replenish the original volume. Repeat the washing process twice to remove excess unreacted PDMS-COO-NHS. The retentate was collected and diluted to 12 mL. The mixture was then ultrasonically dispersed for 5 min to obtain a polydimethylsiloxane / silver nanocomposite dispersion. ICP-OES analysis showed that the silver content in the dispersion was 0.32 mg / mL. The zeta potential of the dispersion was -24.1 mV, and the average particle size was 76 nm. The polydispersity index (PDI) was 0.12.

[0050] (3) Post-treatment: Immerse the dyed fabric from step (2) in a solution containing 1.5 g / L of nonionic soaping agent (such as fatty alcohol polyoxyethylene ether) at a liquor ratio of 1:20 and treat it at 55°C for 13 min. After soaping, wash it with 45°C warm water for 10 min, then wash it with room temperature cold water for 5 min. Finally, heat setting treatment is performed (using a pin plate tenter frame, setting temperature of 115°C, setting time of 85 seconds, overfeed rate of 2%, and width set to 103% of the original width). After setting, cool to room temperature to obtain antibacterial fabric.

[0051] Example 3

[0052] A process for preparing an antibacterial fabric based on a polydimethylsiloxane-silver nanocomposite system includes the following steps:

[0053] (1) Pretreatment: The fabric (polyester fabric - 100% polyester fiber, 180gsm) was treated with caustic soda at a concentration of 13g / L, at a bath ratio of 1:40, at a temperature of 100℃ for 20 minutes and then put into use.

[0054] (2) Dyeing and antibacterial finishing: Immerse the fabric prepared in step (1) into the dyeing solution (including 5% owf of disperse dye, 5% owf of polydimethylsiloxane / nano silver composite dispersion (based on the dry weight of PDMS-Ag composite), 2 g / L of dispersant, and 1 g / L of leveling agent), control the bath ratio to 1:30, first adjust the pH of the dyeing solution to 5.5 with citrate-sodium citrate buffer, keep it at 80℃ for 60 min (so that the polydimethylsiloxane / nano silver composite dispersion is fully adsorbed on the fiber surface), then raise the temperature to 110℃ at a rate of 1.5℃ / min (closed pressure conditions), keep it at 80℃ for 45 min, and cool it down to 80℃ after dyeing. The dyed fabric is ready for use.

[0055] The preparation process of the polydimethylsiloxane / nano silver composite dispersion includes the following steps:

[0056] ① Take 80g of hydroxyl-terminated polydimethylsiloxane (PDMS-OH, with a double-terminated hydroxyl structure, number-average molecular weight of 1500 Da ± 10%, molecular weight distribution ≤ 1.5, and hydroxyl value of 70-80 mg. Dissolve PDMS-COOH (PDMS-OH / g) completely in a 500 mL three-necked flask with 200 mL of anhydrous toluene. Add 13.3 g of succinic anhydride (molar ratio PDMS-OH:succinic anhydride = 1:2.5), 0.16 g of 4-dimethylaminopyridine (DMAP, 0.2% of the mass of PDMS-OH), and 4.5 mL of triethylamine. Heat to 110 °C and reflux for 5 h under nitrogen protection. After the reaction, remove the solvent by rotary evaporation. Redissolve the crude product in 50 mL of anhydrous toluene, then add it dropwise to 300 mL of methanol in an ice bath with stirring. Allow to stand and separate into layers, then remove the supernatant. Repeat the precipitation and purification process twice. Dry to constant weight to obtain a colorless, transparent, viscous PDMS-COOH. Infrared spectroscopy results show that the product is soluble in 1710 cm⁻¹. -1 The presence of a characteristic absorption peak at the C=O stretching vibration of the carboxyl group, combined with acid-base titration detection (the measured carboxyl content was 1.19 mmol / g), confirmed the successful preparation of PDMS-COOH with a double-ended carboxyl group structure.

[0057] ② Take 1.35 g of PDMS-COOH from step ① (titrated to contain 1.6 mmol COOH), dissolve it in 20 mL of anhydrous THF, and stir until completely dissolved; add 613 mg (3.2 mmol) of EDC·HCl and 184 mg (1.6 mmol) of NHS, and slowly add about 100 μL of triethylamine to adjust the system to weakly alkaline; stir the reaction at room temperature in the dark for 4 h; after the reaction is completed, concentrate the THF by rotary evaporation under reduced pressure in a 40 °C water bath, then reconstitute the residue with DCM, wash with dilute hydrochloric acid (0.1 M), and after separation, collect the organic phase, dry it with anhydrous sodium sulfate, filter it, and concentrate it by rotary evaporation (to remove DCM) to obtain activated PDMS-COO-NHS; before use, dilute to volume with anhydrous THF to prepare a stock solution of 20 mg / mL;

[0058] ③ Take 80 mL of pure water, heat it to 97 °C, and add 1.3 mL of 1% (w / v) AgNO3 solution while stirring. Then add 10 mL of 1% (w / v) sodium citrate solution and keep it warm for 25 min. When the solution color changes from colorless to yellow and then to brownish-yellow, cool it to room temperature and centrifuge (centrifuge at 10000 rpm for 20 min at 4 °C). Remove the supernatant and add a buffer solution of pH 8.5 (1 mM sodium citrate solution) to resuspend it. Continue to centrifuge to remove the supernatant, add buffer solution to resuspend the precipitate, and make up the volume to 32 mL to obtain the concentrated and purified AgNPs dispersion (the mass concentration of silver in the AgNPs dispersion is 0.21 mg / mL).

[0059] ④ Take 20 mL of the AgNPs dispersion from step ③, adjust the pH to 8.8 with 0.1 M NaOH solution, and determine the total amount of silver atoms in the dispersion by ICP-OES. Calculate the amount of cysteine ​​to be used based on a cysteine ​​to silver atom molar ratio of 2.8:1. Under nitrogen protection, prepare a 100 mM solution of the calculated amount of cysteine ​​with PBS buffer, and slowly add it dropwise to the AgNPs dispersion at a rate of 1.0 mL / min. React at room temperature for 4 h. After the reaction is complete, transfer the reaction solution to an ultrafiltration tube with a molecular weight cutoff of 10 kDa, and centrifuge at 4℃ and 4000 rpm for ultrafiltration. After concentrating to 1 / 3 of the original volume, add PBS buffer to replenish the original volume, and repeat the washing process 3 times. Collect the retentate and make up to 32 mL with PBS buffer to obtain the aminated AgNPs dispersion.

[0060] ⑤ Take 32 mL of the solution containing aminated AgNPs from step ④. The total mass of silver nuclei was determined to be 4.4 mg by ICP-OES. Transfer the dispersion to a 100 kDa ultrafiltration tube and centrifuge at 4000 rpm at 4℃ to concentrate to 5 mL. Then, add MES buffer (containing 0.1 M NaCl) at pH 6.0 to bring the total volume to 32 mL (repeat this concentration-displacement operation once to completely remove the original buffer system). Transfer the concentrated AgNPs dispersion to a reaction flask and place it in a constant temperature circulating water bath at 15℃ with magnetic stirring (550 rpm). Take 5.1 mL of the PDMS-COO-NHS (20 mg / mL) stock solution from step ② (the required PDMS-COO-NHS mass is calculated to be 101 mg based on a PDMS-COO-NHS to silver nucleus mass ratio of 23:1). Slowly add the solution dropwise to the AgNPs dispersion at a rate of 0.2 mL / min. After the addition is complete, stir the solution at 15 °C for 1.2 h until the reaction is complete. Then add 2.5 times the mass of AgNPs, i.e., 11 mg of PVP K30, and continue stirring for 30 min. Transfer the reaction solution to a 100 kDa ultrafiltration tube and centrifuge at 4 °C and 4000 rpm for ultrafiltration. After concentrating the solution to 1 / 5 of the original volume, add PBS buffer containing 0.1% PVP K30 to replenish the original volume. Repeat the washing process twice to remove excess unreacted PDMS-COO-NHS. The retentate was collected, diluted to 12 mL, and ultrasonically dispersed for 5 min to obtain a polydimethylsiloxane / silver nanocomposite dispersion. The silver content in the dispersion was determined to be 0.30 mg / mL by ICP-OES. The zeta potential of the dispersion was -23.8 mV, and the average particle size was 78 nm and the polydispersity index (PDI) was 0.13, as determined by dynamic light scattering.

[0061] (3) Post-treatment: Immerse the dyed fabric from step (2) in a solution containing 2 g / L of nonionic soaping agent (such as fatty alcohol polyoxyethylene ether) at a liquor ratio of 1:20 and treat it at 60°C for 15 min. After soaping, wash it with 50°C warm water for 10 min, then wash it with room temperature cold water for 8 min. Finally, heat setting treatment is performed (using a pin plate tenter frame, setting temperature of 120°C, setting time of 90 seconds, overfeed rate of 2.5%, and width set to 104% of the original width). After setting, cool it naturally to room temperature to obtain antibacterial fabric.

[0062] To better demonstrate the process method of the present invention and obtain antibacterial fabrics with better antibacterial effects, the following comparative examples are given with reference to Example 2; the antibacterial properties of the antibacterial fabrics in Examples 1-3 and the comparative examples were tested; the test method was performed according to GB / T20944.3-2008 Evaluation of antibacterial properties of textiles Part 3: Oscillation method. The bacteria used for testing were: Gram-negative bacteria: Escherichia coli ATCC 25922; Gram-positive bacteria: Staphylococcus aureus ATCC 6538. The specific test results are shown in Table 2 below.

[0063] Comparative Example 1

[0064] Unlike Example 2, in step (2), instead of adding polydimethylsiloxane / silver nanocomposite dispersion, an equal amount of pure PDMS dispersion without grafted silver nanoparticles was added (the preparation method is the same as steps ①-② of Example 2, but without the silver nanoparticle grafting in steps ③-⑤); the rest of the operations are the same.

[0065] Comparative Example 2

[0066] Unlike Example 2, in step (2), instead of adding polydimethylsiloxane / silver nanocomposite dispersion, an equal amount of pure AgNPs dispersion without grafted PDMS was added to the dye solution (the preparation method is the same as step ③ in Example 2, except that the amination and grafting in steps ④-⑤ are not performed). The remaining operations are the same.

[0067] Comparative Example 3

[0068] Unlike Example 2, the polydimethylsiloxane / silver nanocomposite dispersion added to the dye solution in step (2) was physically mixed from PDMS dispersion (same as Comparative Example 1) and AgNPs dispersion (same as Comparative Example 2) at a mass ratio of 3:1, and no chemical bonding occurred between the two. The remaining operations were the same.

[0069] Comparative Example 4

[0070] Unlike Example 2, step ② of the preparation process of the polydimethylsiloxane / silver nanoparticle composite dispersion does not involve the addition of hydrochloric acid solution of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide solution. This means that PDMS-COOH is not activated and cannot form chemical bonds with aminated AgNPs. The remaining operations are the same.

[0071] Comparative Example 5

[0072] Unlike Example 2, step ④ of the preparation process of the polydimethylsiloxane / silver nanoparticle composite dispersion does not involve the addition of cysteine ​​solution; that is, no amino groups are introduced onto the surface of AgNPs, thus preventing them from forming chemical bonds with activated PDMS. The remaining operations are the same.

[0073] Comparative Example 6

[0074] Unlike Example 2, in step ⑤ of the preparation process of the polydimethylsiloxane / silver nanocomposite dispersion, the mixture was stirred at 23°C after the addition was complete. The remaining operations were the same.

[0075] Comparative Example 7

[0076] Unlike Example 2, in step ⑤ of the preparation process of the polydimethylsiloxane / silver nanocomposite dispersion, the mass ratio of PDMS-COO-NHS in the solution containing PDMS-COO-NHS to the silver core in the solution containing aminated AgNPs is 15:1. The remaining operations are the same.

[0077] Comparative Example 8

[0078] Unlike Example 2, in step (1), the concentration of caustic soda was 18 g / L during the alkali reduction treatment, and the rest of the operation was the same.

[0079] Comparative Example 9

[0080] Unlike Example 2, in step (1), the alkali reduction treatment was carried out at a temperature of 105°C, while the rest of the operation was the same.

[0081] Comparative Example 10

[0082] Unlike Example 2, the treatment temperature in step (2) for staining and antibacterial finishing is 130°C, while the rest of the operations are the same.

[0083]

[0084] The data in Table 2 show that the antibacterial fabric prepared using the process method of Example 2 of the present invention has a better antibacterial effect than other examples and comparative examples.

[0085] It should be noted that the disperse dyes described in this invention can be conventional polyester disperse dyes in the art, such as CI disperse yellow, CI disperse red, CI disperse blue, etc.; the dispersant can be selected from one or more of naphthalene sulfonic acid formaldehyde condensate and lignin sulfonate; the leveling agent can be selected from fatty alcohol polyoxyethylene ether leveling agents. The above-mentioned auxiliaries are all commonly used auxiliaries in the textile printing and dyeing industry, and those skilled in the art can select them according to actual needs.

[0086] It should be noted that in all embodiments of the present invention, the amount of "polydimethylsiloxane / nano silver composite" refers to the percentage of the dry weight of the composite relative to the mass of the fabric. During actual dyeing, the required volume of the dispersion is calculated based on the measured solid content of each batch of composite dispersion (calculated from the silver content and PDMS content), and the initial water volume is adjusted accordingly to maintain the set bath ratio.

[0087] 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, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A preparation process for an antibacterial fabric based on a polydimethylsiloxane-silver nanocomposite system, characterized in that, The fabric is a polyester fiber fabric, and the process includes the following steps: (1) Pretreatment: Reduce the amount of alkali on the fabric to obtain the treated fabric for later use; (2) Dyeing and antibacterial finishing: Immerse the fabric prepared in step (1) into the dyeing solution, and control the bath ratio to 1:20-30; first adjust the pH of the dyeing solution to 5.0-5.5, and keep it at 65-80℃ for 40-60 min; then raise the temperature to 105℃-110℃ at a rate of 1-1.5℃ / min, keep it at 105℃-110℃ for 30-45 min, and after dyeing, cool it down to 65-80℃ to obtain the dyed fabric for use; the dyeing solution contains polydimethylsiloxane / nano silver composite dispersion; (3) Post-processing: The dyed fabric in step (2) is soaped, washed with water and set to obtain antibacterial fabric.

2. The preparation process of an antibacterial fabric based on a polydimethylsiloxane-silver nanocomposite system according to claim 1, characterized in that, In step (1), the concentration of caustic soda is 10-15 g / L, the bath ratio is 1:30-40, the treatment temperature is 95-100℃, and the treatment time is 20-30 min.

3. The preparation process of an antibacterial fabric based on a polydimethylsiloxane-silver nanocomposite system according to claim 1, characterized in that, The dyeing solution mentioned in step (2) includes 1-5% owf of disperse dye, 1-5% owf of polydimethylsiloxane / nano silver composite dispersion, 1-2 g / L of dispersant, and 0.5-1 g / L of leveling agent.

4. The preparation process of an antibacterial fabric based on a polydimethylsiloxane-silver nanocomposite system according to claim 1, characterized in that, The preparation process of the polydimethylsiloxane / silver nanocomposite dispersion in step (2) includes the following steps: ① Hydroxyl-terminated polydimethylsiloxane and succinic anhydride are mixed in a molar ratio of 1:2.5, toluene and catalyst are added, and the mixture is refluxed for 4-5 hours under nitrogen protection. The solvent is removed by rotary evaporation, and the crude product is reconstituted, extracted and dried to obtain PDMS-COOH. ② Take the PDMS-COOH mentioned in step ①, add an organic solvent and stir to dissolve, add a hydrochloric acid solution of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and an N-hydroxysuccinimide solution, stir and react for a period of time, remove the organic solvent by rotary evaporation, then re-dissolve, wash and dry to obtain a solution containing PDMS-COO-NHS. ③ Take 80 mL of pure water, heat it to 95-97℃, add 1.3 mL of 1% (w / v) AgNO3 solution while stirring, then add 10 mL of 1% (w / v) sodium citrate solution, keep the temperature for 15-25 min, wait for the solution color to change from colorless to yellow and then to brownish-yellow, cool to room temperature, centrifuge and purify to obtain AgNPs dispersion; ④ Take the AgNPs dispersion from step ③ and add cysteine ​​solution prepared with PBS buffer dropwise under nitrogen protection and stirring at room temperature to obtain a solution containing aminated AgNPs. ⑤ Take the aminated AgNPs solution from step ④, concentrate it by centrifugation and ultrafiltration, and replace it with pH 6.0 MES buffer containing 0.1M NaCl to obtain an aminated AgNPs dispersion in the buffer. Under stirring and temperature control, slowly add the PDMS-COO-NHS solution from step ② to the above dispersion for reaction. After the reaction is complete, add the dispersant PVP K30 and continue stirring. Then, the reaction solution is centrifuged and ultrafiltered. The collected retentate is repeatedly washed and purified with PBS buffer containing 0.1% PVP K30. The obtained retentate is the polydimethylsiloxane / silver nanocomposite dispersion.

5. The preparation process of an antibacterial fabric based on a polydimethylsiloxane-silver nanocomposite system according to claim 1, characterized in that, In step ②, the molar ratio of COOH in PDMS-COOH to 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide is 1:2:

1.

6. The preparation process of an antibacterial fabric based on a polydimethylsiloxane-silver nanocomposite system according to claim 1, characterized in that, In step ④, the concentration of the cysteamine solution is 50-100 mM.

7. The preparation process of an antibacterial fabric based on a polydimethylsiloxane-silver nanocomposite system according to claim 1, characterized in that, Step ⑤ The mass ratio of the silver cores in the PDMS-COO-NHS solution to the aminated AgNPs solution is 20-25:1.

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