A Recyclable Broad-Spectrum Antibacterial Polylactic Acid Composite Fiber and Its Preparation Method

Abstract

The present invention discloses a recyclable broad-spectrum antibacterial polylactic acid composite fiber and a preparation method thereof, which belongs to the technical field of composite fibers. Among them, the preparation method includes the following steps: adding polylactic acid to dichloromethane for dissolution to obtain a polylactic acid solution; uniformly dispersing nano-cuprous oxide in the polylactic acid solution through coordination bond cross-linking to form a mixed solution; the mass ratio of the nano-cuprous oxide to the polylactic acid is (0.001-0.009):1; after the mixed solution is dried by evaporation, extrusion granulation and melt spinning are carried out to obtain the polylactic acid composite fiber. The present invention utilizes the coordination bond cross-linking effect to introduce nano-cuprous oxide with broad-spectrum antibacterial properties as physical crystallization points into the polylactic acid molecular chain, thereby improving the mechanical properties of the polylactic acid composite fiber and endowing the polylactic acid composite fiber with good antibacterial properties. In addition, due to the easy breakage and regeneration of coordination bonds, the polylactic acid composite fiber prepared by the present invention also has good recyclable performance.

Description

Technical Field

[0001] The present invention relates to the technical field of composite fibers, and specifically to a recyclable broad-spectrum antibacterial polylactic acid composite fiber and a preparation method thereof. Background Art

[0002] At present, more than 90% of textiles are made of polyester chemical fibers such as polyethylene terephthalate (PET). Since these materials do not have broad-spectrum antibacterial functions, they are prone to breeding bacteria and fungi during repeated use, posing a potential threat to consumer health. At the same time, it is difficult to recycle and reuse these materials, and complex process means are often required. There is an urgent need in the current market to develop a new type of fiber material that can meet the needs of the textile market and solve the problems of safety and recyclability.

[0003] Polylactic acid fiber has excellent biocompatibility and mechanical properties, is friendly to human skin, and is an ideal textile raw material. However, although polylactic acid fiber has certain antibacterial ability due to its weak acidity, its broad-spectrum antibacterial performance is poor. For example, it is difficult to inhibit the activity of common pathogenic bacteria such as Candida albicans and Staphylococcus aureus. In this regard, introducing broad-spectrum antibacterial materials into polylactic acid fiber can improve its broad-spectrum antibacterial performance, but the mechanical strength of the prepared broad-spectrum antibacterial polylactic acid composite fiber is reduced due to poor interfacial interaction, making it difficult to meet the mechanical design requirements of textiles. In addition, the poor interfacial interaction also makes the prepared antibacterial polylactic acid fiber difficult to recycle. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method of a recyclable broad-spectrum antibacterial polylactic acid composite fiber to solve the problems raised in the above background art.

[0005] To achieve the above purpose, the embodiments of the present invention provide the following technical solutions:

[0006] A preparation method of a recyclable broad-spectrum antibacterial polylactic acid composite fiber, which includes the following steps:

[0007] Add polylactic acid to dichloromethane for dissolution to obtain a polylactic acid solution;

[0008] Uniformly disperse nano-cuprous oxide in the polylactic acid solution through coordination bond cross-linking to form a mixed solution; the mass ratio of the nano-cuprous oxide to the polylactic acid is (0.001 - 0.009):1;

[0009] After subjecting the mixed solution to a drying treatment, extrusion granulation and melt spinning are carried out to obtain a polylactic acid composite fiber.

[0010] Preferably, the mass ratio of the polylactic acid to the dichloromethane is 1:(8 - 12).

[0011] Preferably, the mass ratio of the cuprous oxide nanoparticles to the polylactic acid is 0.005:1.

[0012] Preferably, the step of uniformly dispersing the cuprous oxide nanoparticles in the polylactic acid solution through coordination bond crosslinking to form a mixture specifically includes:

[0013] Mix the cuprous oxide nanoparticles with the polylactic acid solution and perform ultrasonic dispersion treatment to obtain a mixture.

[0014] Preferably, the ultrasonic frequency of the ultrasonic dispersion treatment is 20 - 40 kHz, and the power is 50 - 100 W.

[0015] Preferably, the temperature of the drying treatment is 45 - 55 °C.

[0016] Preferably, the extrusion granulation is carried out using a twin - screw extruder; the twin - screw temperature zone of the twin - screw extruder is 170 - 200 °C, and the screw rotation speed is 110 - 130 r / min.

[0017] Preferably, in the melt - spinning process, a spinneret with a diameter of 0.6 - 0.8 mm is used, the drawing speed is 250 - 350 r / min, and the spinning temperature is 180 - 200 °C.

[0018] Another object of the embodiments of the present invention is to provide a polylactic acid composite fiber prepared by the above - mentioned preparation method.

[0019] Preferably, the recycling method of the polylactic acid composite fiber is: placing the polylactic acid composite fiber in dichloromethane to redissolve, recycle, and reuse it.

[0020] The preparation method of the polylactic acid composite fiber provided by the embodiments of the present invention introduces cuprous oxide nanoparticles with broad - spectrum antibacterial properties as physical crystallization points into the polylactic acid molecular chain by utilizing coordination bond crosslinking, thereby improving the mechanical properties of the polylactic acid composite fiber and endowing the polylactic acid composite fiber with good antibacterial properties. In addition, since the coordination bond is easy to break and regenerate, the polylactic acid composite fiber prepared by the present invention also has good recyclability, which is expected to enhance the application potential of the polylactic acid composite fiber and its products. Description of the Drawings

[0021] Figure 1 is the external shape diagram of the fibers prepared in Examples 1 - 5;

[0022] Figure 2 is the knitting molding diagram of Example 1;

[0023] Figure 3 is the single - filament load - bearing diagram of Example 1;

[0024] Figure 4 is the surface and cross - section SEM diagram of Example 1;

[0025] Figure 5 are the surface and cross-section SEM images of Examples 6 - 7;

[0026] Figure 6 are the Mapping and EDS spectra of Example 1;

[0027] Figure 7 are the infrared spectra of the comparative example and Example 1;

[0028] Figure 8 are the XRD curves of the comparative example and Example 1;

[0029] Figure 9 are the XPS survey spectra of the comparative example and Example 1;

[0030] Figure 10 are the high-resolution spectra of C1s, O 1s, and Cu2p of the comparative example and Example 1;

[0031] Figure 11 are the stress-strain curves of the comparative example and Examples 1 - 5;

[0032] Figure 12 are the stress-strain curves of Example 1 placed for different times;

[0033] Figure 13 are the colony photos of standard cotton fabric, the comparative example, and Example 1 against Candida albicans, Escherichia coli, and Staphylococcus aureus;

[0034] Figure 14 are the bar charts of the broad-spectrum antibacterial rate comparison of the comparative example, Example 1, and standard cotton fabric;

[0035] Figure 15 is the recycling schematic diagram of Example 10;

[0036] Figure 16 are the surface and cross-section SEM images of Example 10;

[0037] Figure 17 are the colony photos of Example 1 and Example 10 against Candida albicans, Escherichia coli, and Staphylococcus aureus. Detailed implementation manners

[0038] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0039] An embodiment of the present invention aims to provide a broad-spectrum antibacterial polylactic acid composite fiber with recyclable performance. This polylactic acid composite fiber can not only meet the requirements of traditional textiles in terms of mechanical properties, but also significantly improve the broad-spectrum antibacterial performance of textiles and ensure that its recyclable performance is not affected. Through the technical solution provided by the embodiment of the present invention, it is expected to effectively promote the application of polylactic acid fibers in the high-value-added textile market, and at the same time promote the production mode of environmentally friendly and sustainable textiles.

[0040] Specifically, in an embodiment of the present invention, a preparation method of a recyclable broad-spectrum antibacterial polylactic acid composite fiber is provided, which includes the following steps:

[0041] S1. Add polylactic acid to dichloromethane for dissolution to obtain a polylactic acid solution;

[0042] S2. Uniformly disperse nano-cuprous oxide in the polylactic acid solution through coordination bond cross-linking to form a mixed solution; the mass ratio of the nano-cuprous oxide to the polylactic acid is (0.001 - 0.009):1;

[0043] S3. After subjecting the mixed solution to a drying treatment, then perform extrusion granulation and melt spinning to obtain a polylactic acid composite fiber, denoted as Cu 2 O / PLA fiber.

[0044] In the Cu 2 O / PLA fiber prepared by the above preparation method, Cu 2 O is cross-linked with the PLA molecular chain in a coordination bond manner and dispersed in the PLA matrix. Cu 2 O serves as a new physical crystallization point, making the Cu 2 O / PLA fiber exhibit excellent mechanical strength. Under the synergistic effect of the broad-spectrum antibacterial property of Cu 2 O and the natural weak acidity of PLA, the Cu 2 O / PLA fiber exhibits ultra-high broad-spectrum antibacterial performance. In addition, due to the easy breakage and regeneration of coordination bonds, the Cu 2 O / PLA fiber exhibits excellent recyclable performance. Therefore, the polylactic acid composite fiber prepared by the embodiment of the present invention has high mechanical strength, broad-spectrum antibacterial property and recyclability.

[0045] In a preferred embodiment of the present invention, the mass ratio of polylactic acid to dichloromethane is 1:(8 - 12), preferably 1:10.

[0046] In a preferred embodiment of the present invention, the mass ratio of nano-cuprous oxide to polylactic acid is preferably 0.005:1.

[0047] In a preferred embodiment of the present invention, the step of uniformly dispersing cuprous oxide nanoparticles in a polylactic acid solution through coordination bond crosslinking to form a mixture, i.e., the above-mentioned step S2, specifically includes: mixing cuprous oxide nanoparticles with a polylactic acid solution and performing ultrasonic dispersion treatment to obtain a mixture.

[0048] In a preferred embodiment of the present invention, the ultrasonic frequency of the ultrasonic dispersion treatment is 20 - 40 kHz, and the power is 50 - 100 W; preferably, the ultrasonic frequency is 20 kHz and the power is 50 W.

[0049] In a preferred embodiment of the present invention, the temperature of the drying treatment is 45 - 55 °C, preferably 50 °C. In practical applications, the mixture can be placed in an oven at 45 - 55 °C for drying treatment to remove the dichloromethane solvent.

[0050] In a preferred embodiment of the present invention, extrusion granulation is carried out using a twin-screw extruder; the twin-screw temperature zone of the twin-screw extruder is 170 - 200 °C; the screw rotation speed is 110 - 130 r / min, preferably 120 r / min.

[0051] In a preferred embodiment of the present invention, in the melt spinning process, a spinneret with a diameter of 0.6 - 0.8 mm is used, the drawing speed is 250 - 350 r / min, and the spinning temperature is 180 - 200 °C.

[0052] In the above-mentioned embodiment of the present invention, by using ultrasonic dispersion treatment, it is possible to uniformly disperse cuprous oxide nanoparticles in a polylactic acid solution through coordination bond crosslinking, introduce cuprous oxide nanoparticles as physical crystallization points into the polylactic acid molecular chain, thereby improving the mechanical properties of the polylactic acid composite fiber and endowing the polylactic acid composite fiber with good antibacterial properties. In addition, the polylactic acid composite fiber prepared by the present invention through processes such as dissolution, drying treatment, twin-screw extrusion granulation, and melt spinning is convenient for recycling, eliminating the traditional recycling process of polylactic acid such as degradation and repolymerization.

[0053] In another embodiment of the present invention, a method for recycling the above-mentioned polylactic acid composite fiber is also provided: placing the polylactic acid composite fiber in dichloromethane for re-dissolution and recycling.

[0054] Specifically, the method for recycling the above-mentioned polylactic acid composite fiber includes the following steps: mixing the used polylactic acid composite fiber with an appropriate amount of dichloromethane to convert the polylactic acid composite fiber into a new polylactic acid dispersion, recycling the polylactic acid dispersion for use, and preparing a new polylactic acid composite fiber. It should be noted that in the above steps, ultrasonic dispersion technology can be used to quickly dissolve the polylactic acid composite fiber in dichloromethane.

[0055] The following examples are some specific implementation cases and application cases of the present invention in actual applications, but are not limited thereto. It should be noted that in the following examples, polylactic acid, nano-cuprous oxide, dichloromethane, etc. are all commercially available products.

[0056] Example 1: This example provides a method for preparing a recyclable broad-spectrum antibacterial polylactic acid composite fiber, which includes the following steps:

[0057] S1. Add 10 g of polylactic acid to 100 g of dichloromethane for mixing and dissolution to obtain a polylactic acid solution M1.

[0058] S2. Mix the above polylactic acid solution M1 with 0.05 g of nano-cuprous oxide and perform ultrasonic dispersion treatment to obtain a mixed solution M2; wherein, the ultrasonic frequency of the ultrasonic dispersion treatment is 20 kHz and the power is 50 W.

[0059] S3. Place the above mixed solution M2 in an oven at 50 °C for drying to remove the dichloromethane solvent, then perform extrusion granulation through a twin-screw extruder with a temperature range of 170 °C to 200 °C, and then perform melt spinning to obtain a polylactic acid composite fiber, denoted as Cu 2 O / PLA-0.5%; wherein, the screw speed of the twin-screw extruder is 120 r / min; the process of melt spinning is: using a spinneret with a diameter of 0.7 mm, a drawing speed of 300 r / min, and a spinning temperature of 190 °C.

[0060] Example 2: This example provides a method for preparing a recyclable broad-spectrum antibacterial polylactic acid composite fiber, which includes the following steps:

[0061] S1. Add 10 g of polylactic acid to 100 g of dichloromethane for mixing and dissolution to obtain a polylactic acid solution M1.

[0062] S2. Mix the above polylactic acid solution M1 with 0.01 g of nano-cuprous oxide and perform ultrasonic dispersion treatment to obtain a mixed solution M2; wherein, the ultrasonic frequency of the ultrasonic dispersion treatment is 20 kHz and the power is 50 W.

[0063] S3. Place the above mixed solution M2 in an oven at 50 °C for drying to remove the dichloromethane solvent, then perform extrusion granulation through a twin-screw extruder with a temperature range of 170 °C to 200 °C, and then perform melt spinning to obtain a polylactic acid composite fiber, denoted as Cu 2 O / PLA-0.1%; wherein, the screw speed of the twin-screw extruder is 120 r / min; the process of melt spinning is: using a spinneret with a diameter of 0.7 mm, a drawing speed of 300 r / min, and a spinning temperature of 190 °C.

[0064] Example 3: This example provides a method for preparing a reusable broad-spectrum antibacterial polylactic acid composite fiber, which includes the following steps:

[0065] S1. Add 10 g of polylactic acid to 100 g of dichloromethane for mixing and dissolution to obtain a polylactic acid solution M1.

[0066] S2. Mix the above polylactic acid solution M1 with 0.03 g of nano cuprous oxide and perform ultrasonic dispersion treatment to obtain a mixed solution M2; wherein, the ultrasonic frequency of the ultrasonic dispersion treatment is 20 kHz and the power is 50 W.

[0067] S3. Place the above mixed solution M2 in an oven at 50 °C for drying to remove the dichloromethane solvent, then perform extrusion granulation through a twin-screw extruder with a temperature range of 170 °C to 200 °C, and then perform melt spinning to obtain a polylactic acid composite fiber, denoted as Cu 2 O / PLA-0.3%; wherein, the screw speed of the twin-screw extruder is 120 r / min; the process of melt spinning is: using a spinneret with a diameter of 0.7 mm, a drawing speed of 300 r / min, and a spinning temperature of 190 °C.

[0068] Example 4: This example provides a method for preparing a reusable broad-spectrum antibacterial polylactic acid composite fiber, which includes the following steps:

[0069] S1. Add 10 g of polylactic acid to 100 g of dichloromethane for mixing and dissolution to obtain a polylactic acid solution M1.

[0070] S2. Mix the above polylactic acid solution M1 with 0.07 g of nano cuprous oxide and perform ultrasonic dispersion treatment to obtain a mixed solution M2; wherein, the ultrasonic frequency of the ultrasonic dispersion treatment is 20 kHz and the power is 50 W.

[0071] S3. Place the above mixed solution M2 in an oven at 50 °C for drying to remove the dichloromethane solvent, then perform extrusion granulation through a twin-screw extruder with a temperature range of 170 °C to 200 °C, and then perform melt spinning to obtain a polylactic acid composite fiber, denoted as Cu 2 O / PLA-0.7%; wherein, the screw speed of the twin-screw extruder is 120 r / min; the process of melt spinning is: using a spinneret with a diameter of 0.7 mm, a drawing speed of 300 r / min, and a spinning temperature of 190 °C.

[0072] Example 5: This example provides a method for preparing a reusable broad-spectrum antibacterial polylactic acid composite fiber, which includes the following steps:

[0073] S1. Add 10 g of polylactic acid to 100 g of dichloromethane for mixing and dissolution to obtain a polylactic acid solution M1.

[0074] S2. Mix the above-mentioned polylactic acid solution M1 with 0.09 g of nano-cuprous oxide and perform ultrasonic dispersion treatment to obtain a mixed solution M2. Among them, the ultrasonic frequency of the ultrasonic dispersion treatment is 20 kHz and the power is 50 W.

[0075] S3. Place the above-mentioned mixed solution M2 in an oven at 50 °C for drying to remove the dichloromethane solvent, then perform extrusion granulation through a twin-screw extruder with a temperature range of 170 °C to 200 °C, and then perform melt spinning to obtain a polylactic acid composite fiber, denoted as Cu 2 O / PLA-0.9%; among them, the screw speed of the twin-screw extruder is 120 r / min; the process of melt spinning is: using a spinneret with a diameter of 0.7 mm, the drawing speed is 300 r / min, and the spinning temperature is 190 °C.

[0076] Example 6: This example provides a method for preparing a reusable broad-spectrum antibacterial polylactic acid composite fiber, which includes the following steps:

[0077] S1. Add 10 g of polylactic acid to 100 g of dichloromethane for mixing and dissolution to obtain a polylactic acid solution M1.

[0078] S2. Mix the above-mentioned polylactic acid solution M1 with 0.1 g of nano-cuprous oxide and perform ultrasonic dispersion treatment to obtain a mixed solution M2. Among them, the ultrasonic frequency of the ultrasonic dispersion treatment is 20 kHz and the power is 50 W.

[0079] S3. Place the above-mentioned mixed solution M2 in an oven at 50 °C for drying to remove the dichloromethane solvent, then perform extrusion granulation through a twin-screw extruder with a temperature range of 170 °C to 200 °C, and then perform melt spinning to obtain a polylactic acid composite fiber, denoted as Cu 2 O / PLA-1%; among them, the screw speed of the twin-screw extruder is 120 r / min; the process of melt spinning is: using a spinneret with a diameter of 0.7 mm, the drawing speed is 300 r / min, and the spinning temperature is 190 °C.

[0080] Example 7: This example provides a method for preparing a reusable broad-spectrum antibacterial polylactic acid composite fiber, which includes the following steps:

[0081] S1. Add 10 g of polylactic acid to 100 g of dichloromethane for mixing and dissolution to obtain a polylactic acid solution M1.

[0082] S2. Mix the above-mentioned polylactic acid solution M1 with 0.3 g of nano-cuprous oxide and perform ultrasonic dispersion treatment to obtain a mixed solution M2. Among them, the ultrasonic frequency of the ultrasonic dispersion treatment is 20 kHz and the power is 50 W.

[0083] S3. Place the above mixture M2 in an oven at 50 °C for drying to remove the dichloromethane solvent, then perform extrusion granulation through a twin-screw extruder with a temperature range of 170 °C to 200 °C, and then perform melt spinning to obtain a polylactic acid composite fiber, denoted as Cu 2 O / PLA-3%; among them, the screw speed of the twin-screw extruder is 120 r / min; the process of melt spinning is: using a spinneret with a diameter of 0.7 mm, a drawing speed of 300 r / min, and a spinning temperature of 190 °C.

[0084] Example 8: This example provides a method for preparing a recyclable broad-spectrum antibacterial polylactic acid composite fiber, which includes the following steps:

[0085] S1. Add 10 g of polylactic acid to 80 g of dichloromethane for mixing and dissolving to obtain a polylactic acid solution M1.

[0086] S2. Mix the above polylactic acid solution M1 with 0.05 g of nano-cuprous oxide and perform ultrasonic dispersion treatment to obtain a mixture M2; among them, the ultrasonic frequency of the ultrasonic dispersion treatment is 30 kHz and the power is 75 W.

[0087] S3. Place the above mixture M2 in an oven at 45 °C for drying to remove the dichloromethane solvent, then perform extrusion granulation through a twin-screw extruder with a temperature range of 170 °C to 200 °C, and then perform melt spinning to obtain a polylactic acid composite fiber, denoted as Cu 2 O / PLA-3%; among them, the screw speed of the twin-screw extruder is 110 r / min; the process of melt spinning is: using a spinneret with a diameter of 0.6 mm, a drawing speed of 250 r / min, and a spinning temperature of 180 °C.

[0088] Example 9: This example provides a method for preparing a recyclable broad-spectrum antibacterial polylactic acid composite fiber, which includes the following steps:

[0089] S1. Add 10 g of polylactic acid to 120 g of dichloromethane for mixing and dissolving to obtain a polylactic acid solution M1.

[0090] S2. Mix the above polylactic acid solution M1 with 0.05 g of nano-cuprous oxide and perform ultrasonic dispersion treatment to obtain a mixture M2; among them, the ultrasonic frequency of the ultrasonic dispersion treatment is 40 kHz and the power is 100 W.

[0091] S3. Place the above mixture M2 in an oven at 55 °C for drying to remove the dichloromethane solvent, then perform extrusion granulation through a twin-screw extruder with a temperature range of 170 °C to 200 °C, and then perform melt spinning to obtain a polylactic acid composite fiber, denoted as Cu 2O / PLA - 3%; wherein, the screw speed of the twin - screw extruder is 130 r / min; the process of melt spinning is as follows: a spinneret with a diameter of 0.8 mm is used, the drawing speed is 350 r / min, and the spinning temperature is 200 °C.

[0092] Example 10: This example provides a method for recycling and re - preparing a reusable broad - spectrum antibacterial polylactic acid composite fiber, which includes the following steps:

[0093] S1. Cut 10 g of the polylactic acid composite fiber prepared in Example 1 above into pieces, and then add it to 100 g of dichloromethane for mixing and dissolution to obtain a polylactic acid solution M1.

[0094] S2. Perform ultrasonic dispersion treatment on the above - mentioned polylactic acid solution M1 to obtain a polylactic acid dispersion M2; wherein, the ultrasonic frequency of the ultrasonic dispersion treatment is 20 kHz and the power is 50 W.

[0095] S3. Place the above - mentioned polylactic acid dispersion M2 in an oven at 50 °C for drying to remove the dichloromethane solvent, then extrude and pelletize it through a twin - screw extruder with a temperature range of 170 °C to 200 °C, and then perform melt spinning to obtain a recycled and reused polylactic acid composite fiber, denoted as Cu 2 O / PLA - R; wherein, the screw speed of the twin - screw extruder is 120 r / min; the process of melt spinning is as follows: a spinneret with a diameter of 0.7 mm is used, the drawing speed is 300 r / min, and the spinning temperature is 190 °C.

[0096] Comparative example: This comparative example provides a method for preparing a pure polylactic acid fiber, which includes the following steps:

[0097] S1. Add 10 g of polylactic acid to 100 g of dichloromethane for mixing and dissolution to obtain a polylactic acid solution M1.

[0098] S2. Perform ultrasonic dispersion treatment on the above - mentioned polylactic acid solution M1 to obtain a polylactic acid dispersion M2; wherein, the ultrasonic frequency of the ultrasonic dispersion treatment is 20 kHz and the power is 50 W.

[0099] S3. Place the above - mentioned polylactic acid dispersion M2 in an oven at 50 °C for drying to remove the dichloromethane solvent, then extrude and pelletize it through a twin - screw extruder with a temperature range of 170 °C to 200 °C, and then perform melt spinning to obtain a pure polylactic acid fiber, denoted as Neat PLA; wherein, the screw speed of the twin - screw extruder is 120 r / min; the process of melt spinning is as follows: a spinneret with a diameter of 0.7 mm is used, the drawing speed is 300 r / min, and the spinning temperature is 190 °C.

[0100] Performance test: 1. The Cu prepared in Examples 1 - 5 above2 The O / PLA fibers are respectively wound on the wire winding cylinders, as Figure 1 shown (from left to right are Cu 2 O / PLA-0.1%, Cu 2 O / PLA-0.3%, Cu 2 O / PLA-0.5%, Cu 2 O / PLA-0.7%, Cu 2 O / PLA-0.9%), indicating that the polylactic acid composite fiber material provided by the present invention can be continuously prepared.

[0101] 2. The Cu 2 O / PLA fibers prepared in the examples of the present invention are woven into shape to obtain Figure 2 , which indicates that the Cu 2 O / PLA fibers have good weaving performance.

[0102] 3. A 20 g weight is hung on the Cu 2 O / PLA-0.5% fiber of Example 1, as Figure 3 shown. It can be seen from the figure that the fiber does not break, indicating its excellent mechanical strength.

[0103] 4. The surface and cross-section of the Cu 2 O / PLA-0.5% prepared in Example 1 are placed under an ion sputtering instrument for 30 seconds to obtain Figure 4 the SEM image of. It can be seen that the Cu 2 O / PLA-0.5% has a smooth surface and cross-section, and there is no aggregation of particulate matter.

[0104] 5. The surface and cross-section of the Cu 2 O / PLA-1%, Cu 2 O / PLA-3% prepared in Examples 6-7 are placed under an ion sputtering instrument for 30 seconds to obtain Figure 5 the SEM image of. It can be seen that when the amount of cuprous oxide introduced is excessive, it will make the surface rough and there is obvious aggregation of particulate matter. Excessive cuprous oxide will agglomerate in the polylactic acid matrix, affecting its morphology and performance.

[0105] 6. The cross-section of the Cu 2 O / PLA-0.5% prepared in Example 1 is characterized in the surface scanning mode of energy dispersive X-ray spectroscopy (EDS) to obtain Figure 6 . It can be seen from the figure that in the cross-section structure of the Cu 2 O / PLA-0.5%, three elements of C, O, and Cu coexist, and the contents are 70.83%, 28.81%, and 0.36% respectively. In addition, it can also be seen from Figure 6 that on the cross-section of the fiber, the Cu 2O in Cu 2 The cross-section of O / PLA fibers is uniformly dispersed.

[0106] 7. Place the Neat PLA prepared in the comparative example and the Cu 2 O / PLA prepared in the example in a Fourier transform infrared spectrometer to obtain the infrared spectrogram of the above materials, as Figure 7 shown. From Figure 7 it can be seen that the C=O vibration peak at 1750 cm -1 has a slight blue shift, indicating that the cuprous ions in cuprous oxide form a coordination bond with the carbonyl group in polylactic acid. Due to the coordination effect, cuprous oxide can be well dispersed in polylactic acid, laying a molecular structure foundation for the good mechanical properties of the Cu 2 O / PLA fibers in the example.

[0107] 8. Place the Neat PLA prepared in the comparative example and the Cu 2 O / PLA-0.5% prepared in Example 1 in an X-ray diffractometer to obtain the XRD curve of the above materials, as Figure 8 shown. From Figure 8 it can be seen that the diffraction peaks of Neat PLA at 16.7° and 19.1° correspond to the

[200] and

[203] crystal planes respectively. The Cu 2 O / PLA-0.5% fibers also show diffraction peaks at 16.7° and 19.1°, indicating that a small amount of cuprous oxide does not change the crystal form structure of polylactic acid.

[0108] 9. Use X-ray photoelectron spectroscopy technology to characterize the chemical element environment changes of the Neat PLA prepared in the comparative example and the Cu 2 O / PLA-0.5% prepared in Example 1 to obtain the XPS total spectrum, as Figure 9 shown. From Figure 9 it can be seen that typical C1s and O1s binding energy signal peaks appear in Neat PLA at 283.48 eV and 531.17 eV. Compared with Neat PLA, two new peaks appear in the Cu 2 O / PLA fibers at 933.46 eV and 952.29 eV, which are attributed to the binding energy signal peaks of Cu 2p2 / 3 and Cu2p1 / 3 respectively. This indicates that Cu 2 O has been successfully introduced into PLA.

[0109] 10. According to the same method above, obtain the fine spectra of C1s, O 1s, and Cu 2p of the Neat PLA prepared in the comparative example and the Cu 2 O / PLA-0.5% prepared in Example 1, as Figure 10 shown. From Figure 10It can be seen that on the Cu 2 O / PLA fiber, the position of the C 1s signal peak did not change, indicating that C atoms did not directly interact with Cu atoms. In the O 1s signal peak, a new peak appeared at 531.0 eV, corresponding to the Cu:O coordination bond. This indicates that there is an interaction between O atoms and Cu atoms. In addition, the binding energy of the C=O bond shifted from 533.8 eV to 533.4 eV, which is considered to be the formation of a coordination bond between Cu and O atoms in the carbon-oxygen double bond, resulting in the migration of the electron cloud. From the Cu 2p fine spectrum, it can be seen that due to the effect of the Cu:O coordination bond, the Cu 2 O / PLA fiber also showed a shift in the Cu 2p binding energy. At the same time, there was no shake-up peak of divalent copper in the spectrum, indicating that Cu 2 O stably exists in the PLA matrix and did not undergo oxidation during the preparation process.

[0110] 11. Cut the Neat PLA prepared in the comparative example and the Cu 2 O / PLA (Cu 2 O / PLA-0.1%, Cu 2 O / PLA-0.3%, Cu 2 O / PLA-0.5%, Cu 2 O / PLA-0.7%, Cu 2 O / PLA-0.9%) prepared in Examples 1-5 into pieces 60 mm long, connect them to a universal material testing machine, control the tensile rate at 5 mm / min, conduct a stress-strain experiment, and obtain a stress-strain curve graph and a comparison graph of various mechanical properties, as shown in Figure 11 shown. Figure 11 It shows that after adding Cu 2 O, the prepared Cu 2 O / PLA has good mechanical properties.

[0111] 12. Place the Cu 2 O / PLA-0.5% prepared in Example 1 at normal temperature and pressure for 6 months, and test its mechanical properties with the same operation as above to obtain Figure 12 . From Figure 12 it can be seen that after being placed for 6 months, the elongation at break decreased, but its tensile strength decreased slowly. This indicates that under normal conditions, the prepared Cu 2 O / PLA fiber has long-term stability and can be used and stored for a long time.

[0112] 13. According to the GB / T 20944.3-2008 Evaluation Standard for Broad-spectrum Antibacterial Properties of Textiles, the standard cotton fabric and the Cu 2The broad-spectrum antibacterial properties of CuO / PLA fibers and the control Neat PLA fibers against Candida albicans, Escherichia coli, and Staphylococcus aureus are shown in the colony photos as Figure 13 follows. It can be seen that there are almost no colonies in the petri dish with Cu 2 O / PLA fibers, while there are still many colonies in the petri dish with Neat PLA. The results show that Cu 2 O / PLA fibers have excellent broad-spectrum antibacterial properties.

[0113] 14. The broad-spectrum antibacterial rates of Cu 2 O / PLA-0.5% prepared in Example 1, the control Neat PLA, and standard cotton fabric were tested and calculated according to GB / T 20944.3-2008, and a bar chart of the comparison of broad-spectrum antibacterial rates was obtained, as shown in Figure 14 the following figure. Figure 14 It shows that Cu 2 O / PLA-0.5% prepared in Example 1 has an excellent broad-spectrum antibacterial rate, all reaching over 99%, far exceeding the standard cotton fabric and the control Neat PLA.

[0114] 15. The recycling of Cu 2 O / PLA fibers is shown in Figure 15 the following figure. Through dissolution and re-spinning treatment, Cu 2 O / PLA-R fibers can be recycled.

[0115] 16. The surface and cross-section of the recycled Cu 2 O / PLA-R fibers in Example 10 were placed under an ion sputtering instrument for 30 seconds to obtain SEM images, as shown in Figure 16 the following figure. It can be seen from Figure 16 the figure that the recycled fibers still maintain a smooth surface and cross-section, and the nanoparticles do not agglomerate in the polylactic acid matrix.

[0116] 17. According to the evaluation standard of broad-spectrum antibacterial properties of textiles GB / T 20944.3-2008, the broad-spectrum antibacterial properties of the recycled Cu 2 O / PLA-R fibers in Example 10 against Candida albicans (C. albicans), Escherichia coli (E. coli), and Staphylococcus aureus (S. aureus) were studied by the oscillation method. It can be seen from Figure 17 the figure that there are almost no colonies in the petri dish with the fibers recycled by solvent and re-spun, indicating that the recycled fibers still have excellent broad-spectrum antibacterial properties.

[0117] In summary, the Cu 2O / PLA fibers have excellent broad-spectrum antibacterial properties, high mechanical strength and recyclability, and thus have high practical value in the field of polylactic acid fibers.

[0118] Inspired by the ideal embodiments of the present invention described above, through the above description, relevant staff can make various changes and modifications without departing from the technical idea of the present invention. The technical scope of the present invention is not limited to the content in the specification.

Claims

1. A method for preparing recyclable broad-spectrum antibacterial polylactic acid composite fiber, characterized in that: The following steps are involved: Adding polylactic acid into dichloromethane to dissolve it, to obtain a polylactic acid solution; The nano-cuprous oxide is uniformly dispersed in the polylactic acid solution through coordination bond cross-linking to form a mixed solution; the mass ratio of the nano-cuprous oxide to the polylactic acid is (0.001-0.009):1; After the mixed solution is evaporated, extrusion granulation and melt spinning are performed to obtain polylactic acid composite fibers; The mass ratio of the polylactic acid to dichloromethane is 1:(8-12); The step of uniformly dispersing nano cuprous oxide in a polylactic acid solution through coordination bond cross-linking to form a mixed solution specifically comprises: The nano cuprous oxide and the polylactic acid solution are mixed and subjected to ultrasonic dispersion treatment to obtain a mixed solution; The melt spinning process uses a spinneret with a diameter of 0.6-0.8 mm, a drawing speed of 250-350 r / min, and a spinning temperature of 180-200°C.

2. The method for preparing polylactic acid composite fiber according to claim 1, characterized in that: The mass ratio of the nano cuprous oxide to the polylactic acid is 0.005:

1.

3. The method for preparing polylactic acid composite fiber according to claim 1, characterized in that: The ultrasonic frequency of the ultrasonic dispersion treatment is 20-40kHz and the power is 50-100W.

4. The method for preparing polylactic acid composite fiber according to claim 1, characterized in that: The temperature of the evaporation treatment is 45-55°C.

5. The method for preparing polylactic acid composite fiber according to claim 1, characterized in that: The extrusion granulation is carried out by a twin-screw extruder; the twin-screw temperature zone of the twin-screw extruder is 170-200° C., and the screw speed is 110-130 r / min.

6. A polylactic acid composite fiber prepared by the preparation method according to any one of claims 1 to 5.

7. The polylactic acid composite fiber according to claim 6, characterized in that The polylactic acid composite fiber recovery method comprises: placing the polylactic acid composite fiber in dichloromethane to re-dissolve and recycle it.

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