Preparation method of antibacterial and antiviral functional yarn and product thereof

Abstract

The invention discloses a preparation method of antibacterial and antiviral functional yarns and a product thereof, the preparation method comprises the following steps: heating a screw, a pipeline, a metering pump and a die head to 240-280 DEG C, setting the spinning speed to 3200-4000 m / min, and then pouring into a pure matrix for slicing and discharging; and after the melt uniformly flows out, mixing the antibacterial and antiviral nano cellulose and chinlon matrix slices according to the proportion of 0.3%-2.5%, pouring the mixture into a charging barrel, installing a filament collecting part after the blanking is stable, starting a cooling and air compression device, and finishing spinning through a filament suction device and a traction device. The antibacterial and antiviral nano-cellulose is uniformly dispersed on the surface and inside of a chinlon matrix through melt blending spinning, a nano-scale structure is maintained, the bacteriostasis rate on common pathogenic bacteria such as staphylococcus aureus and escherichia coli after 20 times of soaping is still greater than or equal to 95%, the mechanical property meets the textile processing and use requirements, the long-acting antibacterial and antiviral characteristics are achieved, and the antibacterial and antiviral chinlon fabric has a good antibacterial and antiviral effect. The preparation process is simple and controllable, and is suitable for large-scale production.

Description

Technical Field

[0001] This invention relates to the field of functional textile materials technology, specifically to a method for preparing antibacterial and antiviral functional yarn and its product. Background Technology

[0002] With the increasing global awareness of public health and the popularization of health-conscious consumption, antibacterial and antiviral textile materials have become one of the core development directions of the textile industry, widely used in medical protection, maternal and infant products, sportswear, home textiles, public transportation seat fabrics, and many other fields. The market has placed higher demands on the antibacterial long-lasting effect, mechanical stability, and safety and non-toxicity of materials. However, the existing antibacterial yarn preparation technology still has many pain points that need to be addressed: traditional technologies often use finishing processes (such as padding, coating, spraying, etc.) to attach antibacterial agents to the fiber surface. This method has the problem of weak bonding between antibacterial agents and fibers, and easy shedding and loss. This not only leads to short-lasting antibacterial effects, with the antibacterial rate usually dropping below 80% after 5-10 washes, which cannot meet the requirements, but may also cause skin irritation or secondary environmental pollution due to the shedding of antibacterial agents. Meanwhile, while existing melt blending spinning technology can achieve the combination of antibacterial agents and matrix, it has significant limitations: First, the choice of matrix material is limited, mostly concentrated on a single type of nylon or polyester, making it difficult to adapt to the performance requirements of different scenarios; second, the types of antibacterial agents are limited, with traditional organic antibacterial agents having poor heat resistance and easily decomposing to produce harmful substances, while inorganic antibacterial agents (such as early nano-silver) have problems of uneven dispersion and severe agglomeration, leading to defects in the fiber interior and a significant decrease in mechanical properties, failing to meet the requirements of processes such as drafting and weaving in textile processing; third, the design of process parameters is rigid, with narrow ranges for key parameters such as temperature and spinning speed, leading to problems such as melt fracture and uneven fiber thickness during production, resulting in poor stability in large-scale production. Furthermore, with the continuous upgrading of industry standards, existing technologies are no longer sufficient to meet the market's urgent demand for multifunctional, high-performance antibacterial and antiviral yarns. Therefore, developing a universally applicable and controllable process for preparing antibacterial and antiviral functional yarns that offers long-lasting and stable antibacterial effects and excellent mechanical properties has become crucial for addressing industry pain points and driving the upgrading of antibacterial textile materials. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for preparing antibacterial and antiviral functional yarn and its product. The method involves melt blending and spinning to uniformly disperse antibacterial and antiviral nanocellulose on the surface and inside of a nylon matrix, maintaining a nanoscale structure. After 20 soaping washes, the antibacterial rate against common pathogenic bacteria such as Staphylococcus aureus and Escherichia coli is still ≥95%. The mechanical properties meet the requirements of textile processing and use, and it has long-lasting antibacterial and antiviral properties. The preparation process is simple and controllable, and it is suitable for large-scale production.

[0004] This invention is implemented as follows: A method for preparing an antibacterial and antiviral functional yarn includes the following steps: (1) Preheating preparation: Turn on the heating devices of the screw, pipeline, metering pump and die head, adjust the screw temperature to 240-280℃, set the spinning speed to 3200-4000m / min, pour in pure nylon matrix chips for discharge, until the melt flows out evenly from the spinneret; the discharge time of the pure polyamide matrix chips is 10-30min to ensure that there are no impurities left in the spinning channel; (2) Raw material mixing and feeding: Take antibacterial and antiviral nanocellulose and nylon matrix chips according to the proportion. The addition ratio of antibacterial and antiviral nanocellulose is 0.3%-2.5% of the mass of polyamide matrix chips. Pour the mixed raw materials into the feed cylinder. After the material flow stabilizes, install the yarn take-up component and turn on the cooling device and air compression device. The cooling device is a side blowing device or a ring blowing device, and the cooling temperature is 20-30℃. The preparation method of antibacterial and antiviral nanocellulose is as follows: a. Pre-treat the nanocellulose to obtain a uniformly dispersed nanocellulose system; b. Add the crosslinking agent epichlorohydrin to the system in step a, and react under certain temperature and pH conditions to allow the hydroxyl groups on the surface of nanocellulose to undergo a ring-opening reaction with the epoxy groups of epichlorohydrin, thereby introducing active ether bonds and hydroxyl groups to obtain modified nanocellulose. c. Add vitamin K or its derivative to the modified nanocellulose system of step b, and stir the reaction under light-protected conditions to allow the quinone or hydroxyl groups of vitamin K or its derivative to undergo a covalent grafting reaction with the active groups on the surface of the modified nanocellulose. d. After the reaction is complete, antibacterial and antiviral nanocellulose materials are obtained; (3) Spinning and forming: Start the suction device to suck up the yarn, turn on the traction device, and complete the spinning.

[0005] Furthermore, in the preparation method of the antibacterial and antiviral nanocellulose, the pretreatment in step a is ultrasonic dispersion or mechanical stirring dispersion, and the concentration of the nanocellulose system is 0.1~1.5wt%; The reaction temperature in step b is 80~130℃, the pH value is 8~11, the mass ratio of epichlorohydrin to nanocellulose is 1~3:1, and the reaction time is 2~6h; In step c, the mass ratio of vitamin K or its derivative to nanocellulose is 1~2:1, the reaction temperature is 60~100℃, and the reaction time is 6~12h.

[0006] Furthermore, the preparation method of the nanocellulose is as follows: (1) Raw material pretreatment: The bamboo pulp board is crushed by a crusher to obtain crushed bamboo pulp; (2) Enzymatic hydrolysis: Add citric acid / sodium citrate buffer solution with pH 5 and diluted cellulase solution to bamboo pulp. Perform enzymatic hydrolysis at 45-55℃ with stirring for 9-11 hours. The ratio of the amount of oven-dried pulp to citric acid / sodium citrate buffer solution is 4-5g:100mL. The amount of cellulase is 5-10% of the mass of oven-dried pulp. The stirring rate is 90-120r / min. (3) High temperature treatment: After the enzymatic hydrolysis reaction is completed, place the enzymatic hydrolysate in a water bath at 90-100℃ and heat for 20-30 minutes; (4) Ultrasonic treatment: The precipitate after high-temperature treatment is transferred into an ultrasonic reactor with an ultrasonic power of 450-550W and an ultrasonic frequency of 30-50kHz for 1-7 hours. (5) Centrifugation and washing: Centrifuge the ultrasonically treated suspension at high speed, collect the supernatant, and repeatedly centrifuge and wash the precipitate until a colloidal solution appears on the upper layer; (6) Product collection: The colloidal solution is collected as a nanocellulose suspension, which is then freeze-dried under vacuum to obtain nanocellulose powder.

[0007] Furthermore, the nanocellulose is plant-derived nanocellulose.

[0008] Furthermore, the nylon matrix chips are selected from one or a mixture of two of PA6 and PA66.

[0009] Furthermore, the proportion of antibacterial, antimicrobial, and antiviral nanocellulose added is 0.8%-1.2% of the mass of the polyamide matrix slices.

[0010] Furthermore, an antibacterial and antiviral functional yarn obtained by the preparation method is formed by melt blending and spinning of antibacterial nanomaterials and nylon matrix, wherein the antibacterial nanomaterials maintain a nanoscale structure and are uniformly dispersed on the surface and inside of the polyamide fiber.

[0011] Furthermore, the yarn maintains an antibacterial rate of ≥95% against at least one pathogenic bacterium, namely Staphylococcus aureus and Escherichia coli, even after 20 washes.

[0012] The present invention has the following advantages: After 20 washes, the product of this invention still maintains an antibacterial rate of ≥95% against common pathogenic bacteria such as Staphylococcus aureus, Escherichia coli, and Candida albicans, demonstrating excellent long-lasting antibacterial properties and solving the problem of poor washability of traditional antibacterial yarns. This invention optimizes the addition ratio of antibacterial and antiviral nanocellulose (0.8%-1.2% is the optimal range), which can be used as a reinforcing phase to improve fiber toughness, meeting the textile processing and usage needs of different scenarios such as clothing, home textiles, and medical protective equipment. The antibacterial nanomaterials maintain a nanoscale structure during spinning, forming a stable bond with the nylon matrix without obvious interface defects, thus improving product lifespan. Simultaneously, the matrix can be made of mainstream polyamide materials such as PA6 and PA66. The process parameters have a wide range (temperature 240-280℃, speed 3200-4000m / min), making it suitable for large-scale industrial production.

[0013] Furthermore, the antibacterial and antiviral nanocellulose material used in the raw materials of this invention can significantly kill Gram-positive and Gram-negative bacteria after 30 minutes of sunlight irradiation, and also has a good inactivation effect on viruses; the vitamin K of this invention is grafted through covalent bonds, which is not easy to fall off, has a long service life, and the vitamin K is non-toxic and has high safety; the product of this invention can use natural light or ordinary light to start the antibacterial reaction, without the need for special equipment, and is highly convenient. Attached Figure Description

[0014] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0015] Figure 1 This is a schematic diagram of the nanocellulose preparation process in an embodiment of the present invention; Figure 2 This is a graph showing the effect of enzyme dosage on the yield of nanocellulose in the embodiments of the present invention. Figure 3 This is a graph showing the effect of enzymatic hydrolysis temperature on the yield of nanocellulose in an embodiment of the present invention. Figure 4 This is a graph showing the effect of enzymatic hydrolysis time on the yield of nanocellulose in an embodiment of the present invention. Figure 5 This is a graph showing the effect of ultrasonic time on the yield of nanocellulose in an embodiment of the present invention. Figure 6 These are macroscopic morphology images of nanocellulose in the embodiments of the present invention (a is a suspension, b is powder). Figure 7 These are microscopic morphology diagrams of bamboo pulp fibers (a, b) and nanocellulose (c) in embodiments of the present invention; Figure 8 This is a diagram showing the diameter (a) and length (b) size distribution of nanocellulose in an embodiment of the present invention; Figure 9The XRD patterns of bamboo pulp fiber and nanocellulose in the embodiments of the present invention are shown below. Figure 10 The XRD patterns of samples treated with different ultrasonic times in this embodiment of the invention; Figure 11 The FTIR spectra of bamboo pulp fiber and nanocellulose in the embodiments of the present invention are shown below. Figure 12 The TG(a) and DTG(b) curves of bamboo pulp fiber and nanocellulose in the embodiments of the present invention are shown. Figure 13 This is a graph showing the transmittance variation of samples with different ultrasound times in an embodiment of the present invention. Figure 14 This is a comparison image of samples before and after being left to stand for 24 hours for different ultrasonic times in an embodiment of the present invention.

[0016] Figure 15 This is a comparison diagram of the morphological structure of plant-derived nanocellulose and antibacterial and antiviral nanocellulose in the embodiments of the present invention.

[0017] Figure 16 This is a diagram illustrating the mechanism of action of the antibacterial and antiviral nanocellulose material in the embodiments of the present invention.

[0018] Figure 17 The images show the appearance of PA yarn products with different concentrations of antibacterial and antiviral nanocellulose powder added in the embodiments of the present invention.

[0019] Figure 18 This is a stress-strain diagram of PA yarn with different concentrations of antibacterial and antiviral nanocellulose powder in the embodiments of the present invention.

[0020] Figure 19 The following are test results for the antibacterial stability of a 1% concentration antibacterial PA6 fabric in an embodiment of the present invention. (a) shows the relationship between the number of soaping cycles and the antibacterial rate of the 1% concentration antibacterial PA6 fabric, and (b) shows the relationship between the number of soaping cycles and the antibacterial effect of the 1% concentration antibacterial PA6 fabric. Detailed Implementation

[0021] The following will be combined with the appendix Figure 1-19 The technical solution of the present invention will be clearly and completely described in detail with specific embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0022] Example 1 I. Preparation of Nanocellulose Bamboo pulp boards were crushed using a pulverizer to obtain pulverized pulp. 100 mL of citric acid / sodium citrate buffer (pH 5) and a certain amount of diluted enzyme solution were added to a beaker containing 4 g of oven-dried pulp. The mixture was stirred at a certain temperature and a stirring rate of 100 r / min. After the reaction time was reached, the enzymatic hydrolysate was heated in a 100 ℃ water bath for 20 min. The precipitate was transferred to an ultrasonic reactor and treated with an ultrasonic power of 500 W and an ultrasonic frequency of 40 kHz for a certain time. The resulting suspension was centrifuged at high speed, and the supernatant was collected to determine the reducing sugar (RS) content. The mixture was centrifuged and washed until a colloidal solution appeared in the upper layer. This colloidal solution was collected as cellulose nanofiber (CNF). The remaining fibers (RF) were collected, dried, and weighed. The preparation process is as follows: Figure 1 As shown. First, a single-factor experiment was conducted, and five experimental parameters were selected for each factor to determine the range of experimental parameters for each factor. Then, an L9(33) orthogonal array design was used to optimize the three main factors affecting CNF yield: enzyme dosage (7%, 8%, 9%), hydrolysis time (9 h, 10 h, 11 h), and hydrolysis temperature (45 ℃, 50 ℃, 55 ℃), thereby determining the optimal preparation scheme.

[0023] The total volume of the nanocellulose suspension prepared under specific conditions was measured. 25 mL of the suspension was measured into a crystallizing dish and freeze-dried under vacuum until constant weight. The yield of CNF was calculated using Equation 2-5. (2-5) In the formula: m1 is the total mass of the dried sample and crystallizing dish, g; m2 is the mass of the crystallizing dish, g; m is the mass of bamboo pulp fiber, g; V is the total volume of the nanocellulose suspension prepared under these conditions, mL.

[0024] The reducing sugar yield of the hydrolysate (collected centrifugal supernatant) was determined using the DNS method and calculated using formula 2-6. The remaining fiber was calculated using formula 2-7. (2-6) (2-7) In the formula: m3 represents the reducing sugar content obtained by referring to the glucose standard curve, mg; V represents the total volume of the hydrolysate, mL; n represents the dilution factor; m represents the mass of the raw material, g; m5 represents the mass of the remaining fiber after centrifugation.

[0025] (a) Effect of enzyme dosage The effect of enzyme dosage on the yield of nanocellulose and reducing sugars was investigated under the conditions of enzymatic hydrolysis temperature of 50 ℃, enzymatic hydrolysis time of 10 h, and ultrasonic time of 6 h (e.g., Figure 2 (As shown). By Figure 2 It can be seen that with the increase of enzyme dosage, the yield of nanocellulose initially increases and then decreases, while the yield of reducing sugars continues to increase. This may be because at lower enzyme dosages, there are fewer binding sites between cellulase and cellulose, resulting in a lower enzymatic hydrolysis rate. When the enzyme dosage is 6%-8%, as the enzyme dosage increases, more binding sites are provided for cellulase to bind with cellulose, promoting the hydrolysis of amorphous regions and breaking more cellulose glycosidic bonds, thus increasing the CNF yield to a maximum of 62.4%. However, when the enzyme dosage is further increased, the yield of reducing sugars shows an increasing trend, reaching 43.2%, while the CNF yield begins to decrease. This may be because some of the amorphous cellulose on the prepared nanocellulose is hydrolyzed into reducing sugars. Therefore, considering the above factors, an enzyme dosage of 8% is more appropriate.

[0026] (ii) Enzymatic hydrolysis temperature The effect of enzymatic hydrolysis temperature on the yield of nanocellulose and reducing sugars was investigated under the conditions of 8% enzyme dosage, 10 h enzymatic hydrolysis time, and 6 h sonication time (e.g., ). Figure 3 (As shown). By Figure 3 It can be seen that with increasing reaction temperature, the yields of both nanocellulose and reducing sugars show a trend of first increasing and then decreasing. When the reaction temperature reaches 50 ℃, the yields of both nanocellulose (62.6%) and reducing sugars (8.6%) reach their maximum values. This may be because at lower temperatures (40 ℃-45 ℃), cellulase activity is low, and the degree of cellulolysis is low, resulting in lower yields of both nanocellulose and reducing sugars. As the reaction temperature increases, cellulase activity increases, the degree of hydrolysis of bamboo pulp fiber improves, and the yield of nanocellulose increases. However, excessively high temperatures can lead to cellulase inactivation. When the enzymatic hydrolysis temperature rises to 60 ℃, the yield of nanocellulose is only 33.7%, while the yield of reducing sugars approaches zero. Therefore, when the temperature is above 50 ℃, the yields of both nanocellulose and reducing sugars show a decreasing trend with further increases in temperature.

[0027] (iii) Enzymatic hydrolysis time The effect of reaction time on the yield of nanocellulose was investigated under the conditions of enzymatic hydrolysis temperature of 50 ℃, ultrasonic time of 6 h, and enzyme dosage of 8% (e.g., Figure 4 (As shown). By Figure 4It can be seen that the yield of reducing sugars gradually increases with the extension of reaction time, while the yield of nanofibers shows a trend of first increasing and then decreasing. Within the reaction time of 8-10 h, the yield of nanocellulose gradually increases with increasing reaction time; when the enzymatic hydrolysis time reaches 10 h, the yield of nanocellulose reaches its highest point of 62.5%; within the reaction time of 10-12 h, the yield of nanocellulose shows a decreasing trend with increasing reaction time. This is mainly because within the reaction time of 10 h, the easily hydrolyzed amorphous regions of cellulose are degraded, separating nano-sized cellulose filaments, thus increasing the yield of nanocellulose; when the reaction time is higher than 10 h, the hydrolysis of bamboo pulp fiber is more complete, the content of remaining fiber tends to stabilize, the yield of reducing sugars increases, and the yield of nanocellulose gradually decreases, indicating that cellulase begins to further hydrolyze the already generated nanocellulose.

[0028] (iv) Ultrasound time The effect of ultrasonic time on the yield of nanocellulose was investigated under the conditions of enzymatic hydrolysis temperature of 50 ℃, enzyme dosage of 8%, and enzymatic hydrolysis time of 10 h (e.g., Figure 5 (As shown). By Figure 5 It can be seen that with the extension of ultrasonic time, the yield of nanocellulose gradually increases and then tends to plateau, while the content of reducing sugars remains almost unchanged. The yield of nanocellulose reaches its highest value of 62.4% when the ultrasonic time reaches 6 hours. During ultrasonic treatment, ultrasound waves propagate in the cellulose suspension at high frequency, driving the medium to generate a large number of tiny vacuum bubbles in the negative pressure zone. These bubbles then close in the positive pressure zone, producing a cavitation effect. The powerful impact force generated by the bursting of countless vacuum bubbles under pressure can break up the cellulose after enzyme pretreatment, causing it to break down and form nanocellulose. The fact that the reducing sugar content remains almost unchanged during ultrasonic treatment indicates that ultrasonic treatment does not lead to excessive degradation of cellulose.

[0029] (v) Orthogonal Experiment Table 2-5 shows the orthogonal experimental design and its results. The optimal process conditions obtained were 8% enzyme dosage, 50 ℃ enzymatic hydrolysis temperature, and 10 h enzymatic hydrolysis time, resulting in a maximum yield of 62.5% of nanocellulose. This demonstrates that the orthogonal experimental results are in good agreement with the single-factor experimental results. The range of the experimental results shows that the enzymatic hydrolysis temperature had the most significant impact on the yield of nanocellulose (R=23.797), followed by the enzyme dosage (R=14.056), while the effect of enzymatic hydrolysis time was relatively small (R=10.153).

[0030] Table 2-5 Orthogonal experimental design and results

[0031] II. Performance Characterization (I) Morphological Analysis Figure 6(a) is a milky white, stable colloid, obtained by centrifugation and washing to neutral cellulose nanoparticles under the conditions of 8% enzyme dosage, 50 °C enzymatic hydrolysis temperature, 10 h enzymatic hydrolysis time and 6 h sonication time. Figure 6 (b) is the freeze-dried nanocellulose powder.

[0032] like Figure 7 The microstructure of bamboo pulp fiber and CNF is shown. Figure 7 Images (a) and (b) show the morphology of bamboo pulp fibers observed under a scanning electron microscope. Field emission scanning electron microscopy was used to observe the sample morphology. The sample was fixed to a short aluminum rod using a double-sided adhesive carbon ribbon. The sample surface was sputtered with gold to avoid charging effects. Observation was performed using a secondary electron detector inside the lens at 1 kV. Figure 7 It is known that bamboo pulp fibers have a flat rod-shaped structure with a rough surface structure, an average diameter of about 15 μm, and a length of several hundred micrometers. Figure 7 (c) Transmission electron microscopy (TEM) image of the prepared CNF. The microstructure of the sample was observed using TEM. The nanocellulose suspension was diluted in ethanol solution and ultrasonically dispersed for 15 min. Then, one drop of CNF dispersion was added and coated onto a TEM sample grid containing a carbon film. The sample was evaporated in a 40 °C oven for 4 h. CNF imaging was performed using TEM under operating conditions of 120 V. Figure 7 It is known that nanocellulose aggregates in bundles, mainly due to the strong hydrogen bonding between nanoparticles, resulting in strong lateral adhesion and lateral aggregation. This characteristic enables it to provide good reinforcement in composite materials. Therefore, CNF can be prepared by combining enzyme pretreatment with ultrasonic cavitation, but further research is needed on how to effectively control its dispersibility in solvents.

[0033] The length and diameter of 100 nanocellulose samples observed under TEM were measured and statistically analyzed. Their size distribution was then compared and analyzed to obtain a diameter and length size distribution map of CNF, as shown below. Figure 8 As shown, (a) is the diameter and (b) is the length. From Figure 8 It can be observed that CNF diameter is 2-24 nm, of which about 30% is 3-6 nm; length is mainly 50-450 nm, of which about 44% is less than 150 nm in length.

[0034] (II) XRD Analysis Under a tube voltage of 80 kV, a scanning speed of 0.1º / s, using Cu-Kα as the X-ray source, and a Ni plate filter, the scanning range was 2. θThe crystal structure of bamboo pulp fiber and freeze-dried nanocellulose powder was tested using X-ray powder diffraction (XRD) at an angle of 5º-60º. The crystallinity of samples with different ultrasonic times (1-7 h) was compared to analyze the effect of different ultrasonic times on the crystallization properties of the samples. The crystallinity index (CrI) was estimated using the Segal method {Segal, 1959 #56} and calculated using formula (2-8) by measuring the diffraction intensity of the 002 peak and the amorphous region. (2-8) In the formula: I 002 Indicates 2 θ =22.5º, which is the intensity of the 002 crystal plane peak, representing the diffraction intensity of the crystalline region; I am Indicates 2 θ The intensity of the peak at 18º represents the diffraction intensity of the amorphous region.

[0035] Figure 9 The XRD patterns of bamboo pulp fiber and CNF are shown. The figures reveal no significant difference in the positions of the diffraction peaks between bamboo pulp fiber and CNF. Both exhibit three strong peaks at 14.5°, 18°, and 22.5°, corresponding to cellulose peaks at 101° and 10°. The 002 crystal plane indicates that the nanocellulose crystals belong to type I cellulose. Compared with bamboo pulp fiber (crystallinity 63.7%), the crystallinity of CNF increases to 73%. This is because during enzymatic hydrolysis, cellulase can easily attack the amorphous regions with high accessibility and reactivity, causing most of the amorphous regions to participate in the reaction and degrade, resulting in a significant increase in the crystallinity of CNF. Figure 10 X-ray diffraction patterns of bamboo pulp fibers after treatment with ultrasound for different times (1-7 h) are shown, labeled S1, S2, S3, S4, S5, S6, and S7, respectively. Compared with bamboo pulp fibers, the crystallinity of the sample treated with ultrasound for 4 h increased from 63.7% to 69.21%. With ultrasound treatment for 6 h, the crystallinity reached 73%. Further increasing the ultrasound time to 7 h, the crystallinity decreased to 70.92%. This may be because excessively long ultrasound treatment caused excessive mechanical strength to act on some of the ordered crystalline regions, resulting in more irregular areas.

[0036] (III) FTIR Analysis The surface functional groups of bamboo pulp fiber and nanoproduct CNF were analyzed using Fourier transform infrared spectroscopy, and the results are as follows: Figure 11 As shown. By Figure 11 It can be seen that CNF exhibits an absorption peak distribution similar to that of bamboo pulp fiber, and both show the presence of the basic characteristic peaks of cellulose: the absorption peak is located at 3347 cm⁻¹. -1 2900 cm -11058 cm -1 1430 cm -1 These correspond to the absorption peaks of the fiber's inherent hydroxyl groups, the CH symmetry of methylene (-CH2-), the CO of cellulose alcohol, and the stretching vibration of saturated CH, respectively. Furthermore, an absorption peak at 1058 cm⁻¹ was observed. -1 There are many weaker acromions nearby, 1112 cm -1 and 1165 cm -1 These correspond to the CO and CC backbone peaks of the intramolecular ether in cellulose, respectively. 895 cm⁻¹ -1 The COC stretching vibration corresponds to the characteristic β-(1,4)-glycosidic bond. The spectra of CNF and natural cellulose show no significant difference, indicating that the chemical structure of CNF has not changed. This can be explained by the nanoscale effect as the unique characteristics exhibited by CNF.

[0037] (iv) TGA Analysis Thermogravimetric analysis of bamboo pulp fiber and freeze-dried CNF powder was performed using a simultaneous thermal analyzer. Under a N2 atmosphere of 30 mL / min, approximately 10 mg of sample was placed on a platinum dish and heated from 30 °C to 700 °C at a heating rate of 10 °C / min. The thermal stability of bamboo pulp fiber and CNF was compared.

[0038] Figure 12 The TG(a) and DTG(b) spectra of bamboo pulp fiber and CNF are shown in Table 2-6. The thermal analysis data of the samples are also shown. The mass loss of bamboo pulp fiber and CNF at temperatures below 120 °C is due to the volatilization of a small amount of free water adsorbed from the air. The initial thermal decomposition temperature of CNF (250 °C) is lower than that of bamboo pulp fiber (303 °C), and the maximum weight loss rate temperature (300 °C) is also lower than that of bamboo pulp fiber (350 °C). Between 200 and 350 °C, the thermal stability of CNF is lower than that of bamboo pulp fiber. This is because enzymatic hydrolysis causes the long cellulose chains to break, and some small cellulose molecules adsorb onto the CNF surface. At lower temperatures, these small cellulose molecules degrade first. When the temperature is above 350 °C, the thermal stability of the prepared CNF is higher than that of bamboo pulp fiber. At 700 °C, the residual rate of bamboo pulp fiber is 3.4%, while that of CNF is still 15.3%. Cellulose enzymatic hydrolysis is carried out under mild conditions, eliminating amorphous regions and defective crystals while causing minimal damage to perfectly crystalline regions, thus positively contributing to the formation of crystals with enhanced molecular arrangement regularity. The arrangement of cellulose crystals in the crystalline regions has a certain influence on thermal stability, and CNF has potential applications in the field of biocomposite materials where high heat resistance is required.

[0039] Table 2-6 Initial decomposition temperature, maximum weight loss rate temperature, and residual mass of bamboo pulp fiber and CNF

[0040] (v) Transmittance analysis Nanocellulose suspension samples prepared by different ultrasonic times (1-6 h) were diluted to the same concentration (CNF solid content 0.1%), and the transmittance of the samples prepared under different conditions was scanned using a UV spectrophotometer in the wavelength range of 200-700 nm.

[0041] Under the conditions of enzymatic hydrolysis temperature of 50 ℃, enzyme dosage of 8%, and enzymatic hydrolysis time of 10 h, suspension samples prepared for different ultrasonic times were diluted with water to a cellulose concentration of 0.1%, thoroughly shaken, and the transmittance at a wavelength of 700 nm was measured. Figure 13 As shown. By Figure 13 It can be seen that short-term (1-3 h) ultrasonic treatment has little effect on the transmittance of the product, with the transmittance reaching its lowest value at an ultrasonic time of 6 h. This is because the crystallinity of nanocellulose reaches its maximum at 6 h, at which point the molecular arrangement is most regular, and incident light is reflected from the polymer surface, resulting in a loss of transmitted light and thus a decrease in transmittance. To clearly observe the dispersion stability of CNF in water, the diluted sample was allowed to stand for a period of time, and its sedimentation phenomenon was observed. Figure 14 The image shows a comparison of the diluted sample and the sample after standing for 24 hours. Observation revealed that after standing for 24 hours, the sample treated with ultrasound for a short time showed more obvious aggregation. The sample treated with ultrasound for 5 hours showed slight aggregation, while the sample treated with ultrasound for 6 hours was relatively stable and showed almost no sedimentation. This indicates that the sample treated with ultrasound for 6 hours had good dispersibility in water and that the colloid was relatively stable, thus exhibiting the lowest transmittance.

[0042] (vi) Surface charge test The surface charge of nanocellulose suspensions was measured using a Zeta potential analyzer. Table 2-7 shows the Zeta potential values ​​of nanocellulose and bamboo pulp fiber prepared at different ultrasonic times (1-7 h) in aqueous media. The presence of functional groups in the cellulose molecule directly affects the charge carried by the cellulose. As shown in Table 2-7, cellulose is electronegative in aqueous media, which may be due to the presence of negatively charged hydroxyl and uronic acid groups, consistent with the FTIR analysis results. Table 2-7 also shows that CNF (Zeta potential value -32.6 mV) exhibits stronger electronegativity than bamboo pulp fiber (Zeta potential value -8 mV). A higher absolute Zeta potential value indicates stronger electrostatic repulsion, which is beneficial for better dispersion of the substance in water and less prone to aggregation and sedimentation, which is consistent with... Figure 14The observed phenomena are consistent, further indicating that the samples sonicated for 6 hours exhibit stronger dispersion stability. With prolonged sonication, the zeta potential (absolute value) of the nanocellulose shows an increasing trend. This may be because ultrasonic cavitation promotes further dispersion of the nanocellulose, reduces the formation of agglomerates, and thus enhances its dispersibility in aqueous solution, leading to an increase in the zeta potential value.

[0043] Table 2-7 Zeta potentials of nanocellulose suspensions

[0044] In summary, through single-factor experiments and L9 (3³) orthogonal experiments, the optimal process conditions were determined to be 8% enzyme dosage, 50℃ enzymatic hydrolysis temperature, 10h enzymatic hydrolysis time, and 6h ultrasonic time. Under these conditions, the yield of nanocellulose reached a maximum of 62.5%. The nanocellulose prepared by this invention is aggregated in bundles with a diameter of 2-24nm, a length of 50-450nm, a crystallinity of 73%, and a Zeta potential of -32.6mV. The nanocellulose retains the basic chemical structure of cellulose, and its infrared spectrum has characteristic absorption peaks at 3347cm⁻¹, 2900cm⁻¹, 1058cm⁻¹, and 1430cm⁻¹. It contains hydroxyl, methylene, and cellulose alcohol functional groups, exhibits good dispersion stability, thermal stability, and chemical structural integrity, and the preparation process is green, environmentally friendly, and low-cost, making it widely applicable in fields such as biocomposite materials.

[0045] Example 2: Preparation of antibacterial and antiviral nanocellulose (1) Take 1g of plant-derived nanocellulose (the product prepared under the optimal process conditions in Example 1), add 100mL of deionized water, and ultrasonically disperse at 200W power for 20min to obtain a 1wt% nanocellulose suspension. (2) Add 0.1 g epichlorohydrin to the above suspension, adjust the pH to 10 with 1 mol / L sodium hydroxide solution, stir the reaction at 50 °C for 4 h, and keep the pH stable during the reaction. (3) After the reaction was completed, the modified nanocellulose was obtained by centrifugation, washed twice with deionized water, redispersed in 50 mL of deionized water, and 0.05 g of vitamin K was added. The mixture was stirred and reacted at 30 °C in the dark for 8 h. (4) After centrifugation and washing three times, the nanocellulose material was obtained by vacuum drying at 50°C for 6 hours.

[0046] Performance testing: After the material was exposed to sunlight for 30 minutes, its antibacterial and antiviral activities were tested. The bactericidal rate against Staphylococcus aureus (Gram-positive bacteria) and Escherichia coli (Gram-negative bacteria) both reached over 99.2%, and the inactivation rate against influenza virus reached over 98.5%.

[0047] The morphological and structural comparison of plant-derived nanocellulose and antibacterial and antiviral nanocellulose, for example... Figure 15 As shown in the figure, pure nanocellulose (plant-derived nanocellulose) has good dispersibility and exhibits a high aspect ratio rod-shaped nanostructure. The microstructure of antibacterial and antiviral nanocellulose has not changed significantly and still maintains the nanoscale rod-shaped structure of nanocellulose without destroying the original structure.

[0048] Example 3: Preparation of antibacterial and antiviral nanocellulose (1) Take 2g of plant-derived nanocellulose (the product prepared under the optimal process conditions in Example 1), add 200mL of deionized water, and mechanically stir at 1000r / min for 40min to obtain a 1wt% nanocellulose suspension; (2) Add 0.2g epichlorohydrin, adjust the pH to 9, and stir the reaction at 40℃ for 6h; (3) After centrifugation and washing, disperse in 80 mL of deionized water, add 0.08 g of vitamin K derivative, and stir at 35 °C in the dark for 10 h. (4) After washing, vacuum dry at 60℃ for 4 hours to obtain the finished product. Tests show that its sterilization rate against Gram-positive and Gram-negative bacteria exceeds 99.0%, and its virus blocking efficiency reaches over 95%.

[0049] In the preparation process of the antibacterial and antiviral nanocellulose of the present invention, epichlorohydrin is used as a crosslinking agent to form covalent bonds between vitamin K (or its derivatives) and nanocellulose, thereby constructing a photosensitive antibacterial structure. The epoxy groups of epichlorohydrin first undergo a ring-opening reaction with the hydroxyl groups on the surface of nanocellulose, introducing active ether bonds and hydroxyl groups, providing reaction sites for subsequent covalent grafting; the quinone groups or hydroxyl groups (some derivatives) of vitamin K further react with the above-mentioned active groups to achieve a firm grafting.

[0050] The antibacterial and antiviral mechanism of this material is as follows: the grafted vitamin K forms a photosensitive structure, which reacts with oxygen in the air under natural or artificial light to generate highly reactive oxygen species (such as hydroxyl radicals), rapidly disrupting the integrity of bacterial cell membranes and leading to bacterial death; simultaneously, it denatures and inactivates the viral protein coat, rendering it ineffective; the high specific surface area of ​​nanocellulose increases the contact area with bacteria and viruses, improving reaction efficiency, and its fibrous network structure can effectively block virus transmission. The mechanism of action is as follows: Figure 16 As shown.

[0051] Example 4: 1. Preparation of antibacterial and antiviral functional yarns: Raw material preparation: 500g PA6 slices, antibacterial and antiviral nanocellulose powder (addition ratio 0, 0.5%, 1%, 2%). Preheating: Turn on the heating system, adjust the screw temperature to 255℃, synchronize the temperature of the pipeline, metering pump and die head, set the spinning speed to 3600m / min, pour in pure PA6 chips and discharge for 20 minutes until the melt flows out evenly; Mixing and feeding: Mix PA6 chips with antibacterial and antiviral nanocellulose powder evenly, pour into the material cylinder, and install the paper tube after the material flow stabilizes. Turn on the side blowing device (cooling temperature 25℃) and the air compression device. Spinning: Start the suction gun to draw in the yarn, turn on the three-roller traction device (speed 3600m / min) to complete the spinning; before changing the proportion of antibacterial and antiviral nanocellulose, perform a washing process.

[0052] The products are labeled as pure PA6 yarn, 0.5% antibacterial PA6 yarn, 1% antibacterial PA6 yarn, and 2% antibacterial PA6 yarn according to the amount of antibacterial and antiviral nanocellulose powder added. The finished product appearance is as follows: Figure 17 As shown; The antibacterial and antiviral functional yarn of the present invention is made by melt blending antibacterial and antiviral nanocellulose material with polyamide (nylon) matrix to achieve close bonding. It is firmly bonded to the fiber surface through supramolecular action and physical embedding, and is also uniformly dispersed in the fiber interior to form a long-lasting antibacterial mechanism.

[0053] 2. Performance testing of antibacterial and antiviral functional yarns: (1) Take one 10cm sample of pure PA6 and one sample of PA6 yarn with three antibacterial concentrations (0.5%, 1%, and 2%), clamp them on the machine and stretch them until they break. Test the stress and strain. See the details below. Figure 18 .

[0054] Depend on Figure 18 It can be seen that the stress of pure PA6 yarn is greater than that of 1% concentration antibacterial PA6 yarn, which is greater than that of 0.5% concentration antibacterial PA6 yarn, which is greater than that of 2% concentration antibacterial PA6 yarn. This indicates that the addition of antibacterial and antiviral nanocellulose reduces the rigidity of the molecular chain and enhances the chain segment mobility. This change stems from insufficient interfacial compatibility between nanocellulose and the PA6 matrix, leading to a decrease in stress transfer efficiency.

[0055] Because the PA6 matrix without added antibacterial and antiviral nanocellulose is a homogeneous polymer phase, the molecular chains are tightly cross-linked by hydrogen bonds and van der Waals forces, with no interfacial defects, resulting in the strongest stress and the highest tensile strength. The 1% concentration antibacterial PA6 yarn has the second-highest strength, possibly because a suitable amount of antibacterial and antiviral nanocellulose is evenly dispersed, and some nanocellulose can act as a reinforcing phase, improving toughness through interfacial stress transfer. However, the polarity difference between the esterified CNF and PA6 still leads to a decrease in strength. The low strength of the 0.5% concentration antibacterial PA6 may be due to insufficient concentration of antibacterial and antiviral nanocellulose, resulting in uneven dispersion and the formation of localized weak areas, leading to breakage. The lowest strength of the 2% concentration antibacterial PA6 yarn may be due to severe CNF / CA aggregation at high concentrations (electron microscopy shows a rough surface), with large particles becoming stress concentration sources, significantly reducing the material's load-bearing capacity.

[0056] (2) The antibacterial stability of the 1% concentration antibacterial PA6 yarn was woven into a fabric and tested, specifically as follows: Figure 19 As shown in the figure, in the antibacterial performance test, the antibacterial PA6 fabric showed no significant change in the inhibition rate against Staphylococcus aureus and Escherichia coli after 5-20 washes compared to the unwashed state, and remained >95% after 20 washes, indicating its high antibacterial efficacy.

[0057] This indicates that the antibacterial and antiviral nanocellulose is tightly bonded to the nylon matrix through a blending spinning method. This allows the antibacterial and antiviral nanocellulose to not only be firmly bound to the surface of the yarn fibers through supramolecular interactions and physical embedding, but also to be uniformly dispersed inside the yarn fibers, forming a long-lasting antibacterial mechanism.

[0058] While specific embodiments of the present invention have been described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and not intended to limit the scope of the present invention. Equivalent modifications and variations made by those skilled in the art in accordance with the spirit of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing an antibacterial and antiviral functional yarn, characterized in that: Includes the following steps: (1) Preheating preparation: Turn on the heating devices of the screw, pipeline, metering pump and die head, adjust the screw temperature to 240-280℃, set the spinning speed to 3200-4000m / min, pour in pure nylon matrix chips for discharge, until the melt flows out evenly from the spinneret; the discharge time of the pure polyamide matrix chips is 10-30min to ensure that there are no impurities left in the spinning channel; (2) Raw material mixing and feeding: Take antibacterial and antiviral nanocellulose and nylon matrix chips according to the proportion. The addition ratio of antibacterial and antiviral nanocellulose is 0.3%-2.5% of the mass of polyamide matrix chips. Pour the mixed raw materials into the feed cylinder. After the material flow stabilizes, install the yarn take-up component and turn on the cooling device and air compression device. The cooling device is a side blowing device or a ring blowing device, and the cooling temperature is 20-30℃. The preparation method of antibacterial and antiviral nanocellulose is as follows: a. Pre-treat the nanocellulose to obtain a uniformly dispersed nanocellulose system; b. Add the crosslinking agent epichlorohydrin to the system in step a, and react under certain temperature and pH conditions to allow the hydroxyl groups on the surface of nanocellulose to undergo a ring-opening reaction with the epoxy groups of epichlorohydrin, thereby introducing active ether bonds and hydroxyl groups to obtain modified nanocellulose. c. Add vitamin K or its derivative to the modified nanocellulose system of step b, and stir the reaction under light-protected conditions to allow the quinone or hydroxyl groups of vitamin K or its derivative to undergo a covalent grafting reaction with the active groups on the surface of the modified nanocellulose. d. After the reaction is complete, antibacterial and antiviral nanocellulose materials are obtained; (3) Spinning and forming: Start the suction device to suck up the yarn, turn on the traction device, and complete the spinning.

2. The preparation method according to claim 1, characterized in that: In the preparation method of the antibacterial and antiviral nanocellulose, the pretreatment in step a is ultrasonic dispersion or mechanical stirring dispersion, and the concentration of the nanocellulose system is 0.1~1.5wt%. The reaction temperature in step b is 80~130℃, the pH value is 8~11, the mass ratio of epichlorohydrin to nanocellulose is 1~3:1, and the reaction time is 2~6h; In step c, the mass ratio of vitamin K or its derivative to nanocellulose is 1~2:1, the reaction temperature is 60~100℃, and the reaction time is 6~12h.

3. The preparation method according to claim 2, characterized in that: The preparation method of the nanocellulose is as follows: (1) Raw material pretreatment: The bamboo pulp board is crushed by a crusher to obtain crushed bamboo pulp; (2) Enzymatic hydrolysis: Add citric acid / sodium citrate buffer solution with pH 5 and diluted cellulase solution to bamboo pulp. Perform enzymatic hydrolysis at 45-55℃ with stirring for 9-11 hours. The ratio of the amount of oven-dried pulp to citric acid / sodium citrate buffer solution is 4-5g:100mL. The amount of cellulase is 5-10% of the mass of oven-dried pulp. The stirring rate is 90-120r / min. (3) High temperature treatment: After the enzymatic hydrolysis reaction is completed, place the enzymatic hydrolysate in a water bath at 90-100℃ and heat for 20-30 minutes; (4) Ultrasonic treatment: The precipitate after high-temperature treatment is transferred into an ultrasonic reactor with an ultrasonic power of 450-550W and an ultrasonic frequency of 30-50kHz for 1-7 hours. (5) Centrifugation and washing: Centrifuge the ultrasonically treated suspension at high speed, collect the supernatant, and repeatedly centrifuge and wash the precipitate until a colloidal solution appears on the upper layer; (6) Product collection: The colloidal solution is collected as a nanocellulose suspension, which is then freeze-dried under vacuum to obtain nanocellulose powder.

4. The preparation method according to claim 3, characterized in that: The nanocellulose is plant-derived nanocellulose.

5. The preparation method according to claim 1, characterized in that: The nylon matrix chips are selected from one or a mixture of two of PA6 and PA66.

6. The preparation method according to claim 1, characterized in that: The proportion of antibacterial, antimicrobial, and antiviral nanocellulose added is 0.8%-1.2% of the mass of the polyamide matrix slices.

7. An antibacterial and antiviral functional yarn obtained by the preparation method according to any one of claims 1-6, characterized in that: The yarn is formed by melt blending and spinning antibacterial nanomaterials and nylon matrix. The antibacterial nanomaterials maintain a nanoscale structure and are uniformly dispersed on the surface and inside of the polyamide fiber.

8. The antibacterial and antiviral functional yarn according to claim 7, characterized in that: The yarn maintains an antibacterial rate of ≥95% against at least one pathogenic bacterium, including Staphylococcus aureus and Escherichia coli, even after 20 washes.

Images