Modified graphene polylactic acid antibacterial fiber and its preparation method and application

Abstract

The present invention provides a modified graphene polylactic acid antibacterial fiber and its preparation method and application, the fiber is based on polylactic acid, and polylactic acid is uniformly loaded with graphene oxide grafted N-halamine antibacterial material; graphene oxide grafted N-halamine antibacterial material contains photosensitive sulfhydryl group, and is combined with the unsaturated bond in polylactic acid by photosensitive sulfhydryl group. The present invention utilizes silane coupling agent containing photosensitive sulfhydryl group to combine graphene oxide with N-halamine precursor and polylactic acid in the form of chemical bond, thereby avoiding the separation of N-halamine from graphene oxide grafted N-halamine antibacterial material and the loss of graphene oxide grafted N-halamine antibacterial material on antibacterial fiber, so that the antibacterial effect of the prepared antibacterial fiber is stable and the antibacterial timeliness is long. The antibacterial fiber obtained by the present invention has good antibacterial performance, antistatic performance and strong mechanical properties, and has great industrial and market application value.

Description

Technical Field

[0001] The present invention relates to the technical field of antibacterial fabric preparation, and in particular to a modified graphene polylactic acid antibacterial fiber and a preparation method and application thereof. Background Art

[0002] The rampant spread of bacteria and viruses in the world today poses enormous challenges to human survival and social development. Medical filtration products have become a primary defense against bacteria. Among products that filter out pathogens, polylactic acid nonwovens play a crucial role. Polylactic acid fibers and their nonwovens create a weakly acidic environment on the surface of the product, offering certain mildew and antibacterial properties. However, pure polylactic acid fabrics have a less pronounced antibacterial effect, allowing bacteria adsorbed on the fibers to survive.

[0003] To address these issues, the antibacterial modification of graphene-based polylactic acid fibers and their non-woven fabrics has been extensively studied over the past few decades. The invention patent (application number CN 202211052980.0) discloses a graphene-polylactic acid antibacterial masterbatch, its preparation method, and application. A uniformly dispersed graphene oxide dispersion is prepared using a modified Hummers method; a guanidine compound is dissolved in water and added to the graphene oxide dispersion, stirred, and heated. The guanidine compound molecules are entangled on the surface of the two-dimensional graphene oxide sheet structure through electrostatic interaction. The mixture is then filtered, washed, and freeze-dried to obtain a guanidine salt-graphene assembly. Finally, the guanidine salt-graphene assembly is melt-blended with a polylactic acid substrate and extruded and granulated to obtain the graphene-polylactic acid antibacterial masterbatch. However, in this patent solution, the antibacterial guanidine compound molecules are assembled with graphene oxide only through electrostatic interaction, and the guanidine-graphene assembly and the polylactic acid substrate are only physically melt-blended; in subsequent applications, the antibacterial material is prone to the loss of antibacterial molecules or the entire guanidine-graphene assembly, and the antibacterial timeliness is poor.

[0004] In the prior art, there are other methods for preparing resistant polylactic acid fibers, such as combining inorganic antimicrobial agents, organic antimicrobial agents or composite antimicrobial agents with polylactic acid through surface grafting, surface coating and melt blending. Polylactic acid can also be modified into a matrix to give polypropylene antimicrobial groups, thereby improving the antimicrobial properties of polylactic acid. However, many of the currently prepared antimicrobial polylactic acid fibers and their non-woven fabrics have more or less problems such as large amount of antimicrobial agents, easy loss of antimicrobial components, short antimicrobial efficacy, high finishing costs, single functions and serious environmental pollution. This has also promoted the research and development of safer, more efficient and cheaper antimicrobial polylactic acid fibers.

[0005] In view of this, it is necessary to design an improved modified graphene polylactic acid antibacterial fiber and its preparation method and application to solve the above problems. Summary of the Invention

[0006] The present invention aims to provide a modified graphene polylactic acid antibacterial fiber, a preparation method and application thereof. By using a silane coupling agent containing a photosensitive mercapto group to chemically bond graphene oxide to an N-halamine precursor and polylactic acid, respectively, the loss of the graphene oxide-grafted N-halamine antibacterial material is avoided, and the antibacterial timeliness and mechanical strength of the modified graphene polylactic acid antibacterial fiber are improved. The resulting antibacterial fiber has both antibacterial and antistatic properties and strong mechanical properties, and has great market application value.

[0007] To achieve the above-mentioned purpose of the invention, the present invention provides a modified graphene polylactic acid antibacterial fiber, which uses polylactic acid as the fiber substrate, and the polylactic acid is uniformly loaded with graphene oxide grafted N-halamine antibacterial material; the graphene oxide grafted N-halamine antibacterial material contains photosensitive thiol groups, and the graphene oxide grafted N-halamine antibacterial material is combined with the unsaturated bonds in the polylactic acid through the photosensitive thiol groups.

[0008] As a further improvement of the present invention, the mass ratio of the polylactic acid to the graphene oxide grafted N-halamine antibacterial material is 1000:(3-15).

[0009] As a further improvement of the present invention, in step S2, the mass ratio of the lamellar graphene oxide to the mercaptosilane coupling agent is (7-10):100.

[0010] The present invention also provides a method for preparing the modified graphene polylactic acid antibacterial fiber, comprising the following steps:

[0011] S1. Dispersing graphene oxide in deionized water and ultrasonically exfoliating to obtain graphene oxide colloid; adding an alkaline solution to the graphene oxide colloid, stirring at 95-100° C., and after the reaction is completed, washing, filtering, and drying to obtain lamellar graphene oxide;

[0012] S2. Adding the lamellar graphene oxide obtained in step S1 and a mercaptosilane coupling agent in proportion to anhydrous ethanol to prepare a mixed solution, adding an N-halamine precursor and a photoinitiator to the mixed solution, irradiating the solution for 1.0 to 2.0 hours, centrifuging, washing, and vacuum drying to obtain graphene oxide grafted N-halamine antibacterial powder;

[0013] S3, mixing the graphene oxide grafted N-halamine antibacterial powder obtained in step S2 with polylactic acid in a preset ratio, irradiating with light for 0.5 to 1.5 hours, and then adding the mixture to a melt-blowing machine for melt-blowing treatment to obtain a graphene oxide grafted N-halamine melt-blown material;

[0014] S4, soaking the graphene oxide grafted N-halamine melt-blown material in step S3 in sodium hypochlorite for 0.5 to 1.0 h, washing, drying, and heat-treating to obtain the graphene oxide grafted N-halamine antibacterial melt-blown material;

[0015] S5. Melt-spinning the graphene oxide grafted N-halamine antibacterial melt-blown material prepared in step S4 to obtain the modified graphene polylactic acid antibacterial fiber.

[0016] As a further improvement of the present invention, the mass ratio of the lamellar graphene oxide to the mercaptosilane coupling agent is (1-9):100; the added amount of the mercaptosilane coupling agent is 1% to 5% of the mass of the polylactic acid.

[0017] As a further improvement of the present invention, in step S2, the amount of the N-halamine precursor added is 0.5% to 1.5% of the mass of the lamellar graphene oxide, and the amount of the photoinitiator added is 0.5% to 5.0% of the mass of the lamellar graphene oxide.

[0018] As a further improvement of the present invention, in step S5, during the melt spinning, deodorizing particles are added to the graphene oxide grafted N-halamine antibacterial melt-blown material, and they participate in the melt spinning together to obtain modified graphene polylactic acid antibacterial fiber with deodorizing function; the deodorizing particles include one or more of activated carbon particles, nanosilver particles, and active oxygen particles.

[0019] As a further improvement of the present invention, in step S1, the graphene oxide preparation includes the following steps:

[0020] SS1. Add the solid mixture of graphite powder and sodium nitrate to concentrated sulfuric acid in an ice-water bath under magnetic stirring, then slowly add potassium perchlorate and potassium permanganate in batches to react. The reaction temperature should not exceed 20°C and the mixture should be removed after 0.5 to 1.5 hours.

[0021] SS2. The solution treated in step SS1 was stirred at room temperature for 24 hours, diluted with 5% H2SO4 solution, stirred for 0.5 to 1.0 hours, and then H2O2 was added, stirred for 0.5 to 2.0 hours, and centrifuged to obtain a solid substance;

[0022] SS3. The solid material obtained in step SS2 is washed 1 to 3 times with a mixed solution of H2SO4, H2O2 and an HCl solution, respectively, and finally washed with distilled water 1 to 3 times to a pH value of 7. After drying, a yellow-brown precipitate is obtained, which is the graphene oxide.

[0023] As a further improvement of the present invention, in step S2, the mercaptosilane coupling agent includes one of 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltrimethyloxysilane, 3-mercaptopropyltriphenylsilane, and 3-(methylpropoxy)propyltrimethoxysilane; the N-halamine precursor includes one of methacrylamide, 1-allylhydantoin, and 2,4-diamino-6-diallylamino-1,3,5-triazine.

[0024] As a further improvement of the present invention, in step S2, the photoinitiator includes one of benzoin dimethyl ether, isopropylthioxanthone, and triaryl iodonium salt.

[0025] The present invention also provides an application of a modified graphene polylactic acid antibacterial fiber, wherein the modified graphene polylactic acid antibacterial fiber is any one of the above-mentioned items or is prepared by any one of the above-mentioned preparation methods. The modified graphene polylactic acid antibacterial fiber is used to prepare antibacterial non-woven fabrics, and the antibacterial non-woven fabrics are used to prepare one or more antibacterial protective products such as medical masks, medical protective clothing, and industrial clothing.

[0026] The beneficial effects of the present invention are:

[0027] 1. The present invention provides a modified graphene-polylactic acid antibacterial fiber, which uses polylactic acid as the fiber substrate and uniformly loads a graphene oxide-grafted N-halamine antibacterial material into the polylactic acid. The graphene oxide-grafted N-halamine antibacterial material contains photosensitive thiol groups and bonds to unsaturated bonds in the polylactic acid via the photosensitive thiol groups. The present invention utilizes a silane coupling agent containing photosensitive thiol groups to chemically bond the graphene oxide to the N-halamine precursor and polylactic acid, respectively. This prevents the loss of the graphene oxide-grafted N-halamine antibacterial material and improves the antibacterial timeliness and mechanical strength of the modified graphene-polylactic acid antibacterial fiber. The resulting antibacterial fiber has both antibacterial and antistatic properties and strong mechanical properties, and has great market application value.

[0028] 2. The present invention first bonds an N-halamine precursor to graphene oxide by chemical bonding, and simultaneously adds a silane coupling agent containing a photosensitive thiol group to prevent the loss of the N-halamine precursor. The coupling agent can react with graphene oxide, the N-halamine precursor, and polylactic acid. Under light conditions, not only does the N-halamine precursor react again with the active groups on the surface of the graphene oxide through the silane coupling agent, but the photosensitive thiol groups on the graphene oxide also bind to the unsaturated bonds in the polylactic acid by chemical bonding. This prevents the N-halamine from being separated from the graphene oxide-grafted N-halamine antibacterial material and the loss of the graphene oxide-grafted N-halamine antibacterial material on the antibacterial fiber with polylactic acid as the base material, so that the prepared antibacterial fiber or antibacterial non-woven fabric has good antibacterial effect and long antibacterial effect.

[0029] 3. The lamellar graphene oxide selected in the present invention has a large specific surface area, contains a large number of surface active groups, and has a high grafting rate. The addition of a mercaptosilane coupling agent further increases the grafting rate of the graphene oxide, providing more reaction sites for N-halamines and coupling agents containing photosensitive mercapto groups. The presence of photosensitive mercapto groups on the graphene oxide surface enables the graphene oxide-grafted N-halamine antibacterial material to be stably bonded with polylactic acid resin in a short period of time, improving the antibacterial properties and load-bearing strength of the resulting material. Furthermore, the lamellar graphene oxide has excellent electrical conductivity, and after melt blending with polylactic acid, it imparts antistatic properties. Furthermore, the lamellar graphene oxide exhibits anisotropy within the fiber, increasing the strength of the antibacterial fiber, resulting in excellent overall performance when used in antibacterial nonwoven fabrics.

[0030] 4. The present invention modifies graphene oxide for antibacterial properties while giving it a photosensitive mercapto group. By limiting the amount of mercaptosilane coupling agent and N-halamine precursor added, the loss of N-halamine antibacterial agent is avoided while preventing the detachment of graphene oxide. At the same time, the mass ratio of graphene oxide grafted N-halamine antibacterial material to polylactic acid is limited, and the antibacterial performance is maximized on the basis of cost savings, which has the value of industrial mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic flow chart of the preparation method of the modified graphene polylactic acid antibacterial fiber of the present invention.

[0032] Figure 2 This is a diagram showing the molecular structure change process of graphene oxide grafted N-halamine antibacterial powder prepared in Example 1.

[0033] Figure 3 This is an electron microscope image of the modified graphene polylactic acid antibacterial fiber prepared in Example 1. DETAILED DESCRIPTION

[0034] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] It should also be noted here that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the solutions of the present invention are shown in the drawings, while other details that are not closely related to the present invention are omitted.

[0036] In addition, it should be noted that the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0037] A modified graphene-polylactic acid antibacterial fiber uses polylactic acid as the fiber substrate, with a graphene oxide-grafted N-halamine antibacterial material uniformly loaded into the polylactic acid. The graphene oxide-grafted N-halamine antibacterial material contains photosensitive thiol groups, which are bonded to unsaturated bonds in the polylactic acid via the photosensitive thiol groups. The mass ratio of polylactic acid to the graphene oxide-grafted N-halamine antibacterial material is 1000:(3-15), and the mass ratio of the lamellar graphene oxide to the mercaptosilane coupling agent is preferably (7-10):100. The present invention utilizes a silane coupling agent containing a photosensitive mercapto group to chemically bond graphene oxide to an N-halamine precursor and polylactic acid, thereby avoiding the loss of the graphene oxide-grafted N-halamine antibacterial material and improving the antibacterial timeliness and mechanical strength of the modified graphene polylactic acid antibacterial fiber. The obtained antibacterial fiber and antibacterial non-woven fabric have both antibacterial properties, antistatic properties and strong mechanical properties, and have great market application value.

[0038] See also Figure 1 As shown, a method for preparing modified graphene polylactic acid antibacterial fiber comprises the following steps:

[0039] S1. Dispersing graphene oxide in deionized water and ultrasonically exfoliating to obtain graphene oxide colloid; adding an alkaline solution to the graphene oxide colloid, stirring at 95-100° C., and after the reaction is completed, washing, filtering, and drying to obtain lamellar graphene oxide; wherein the ultrasonic power is 60 W and the time is 2-4 h;

[0040] S2. Adding the lamellar graphene oxide obtained in step S1 and the mercaptosilane coupling agent in proportion to anhydrous ethanol to prepare a mixed solution, adding an N-halamine precursor and a photoinitiator to the mixed solution, irradiating the solution for 1.0 to 2.0 hours, centrifuging, washing, and vacuum drying to obtain graphene oxide grafted N-halamine antibacterial powder;

[0041] The mass ratio of the lamellar graphene oxide to the mercaptosilane coupling agent is (1-9):100, and the added amount of the mercaptosilane coupling agent is 1% to 5% of the mass of the polylactic acid; the added amount of the N-halamine precursor is 0.5% to 1.5% of the mass of the lamellar graphene oxide, and the added amount of the photoinitiator is 0.5% to 5.0% of the mass of the lamellar graphene oxide. The present invention performs antibacterial modification on the graphene oxide while imparting it with a photosensitive mercapto group. By limiting the added amounts of the mercaptosilane coupling agent and the N-halamine precursor, the loss of the N-halamine antibacterial agent is avoided while the detachment of the graphene oxide is prevented. At the same time, the mass ratio of the graphene oxide grafted N-halamine antibacterial material to the polylactic acid is limited, and the antibacterial performance is maximized on the basis of cost savings, thus having industrial mass production value.

[0042] S3, mixing the graphene oxide grafted N-halamine antibacterial powder obtained in step S2 with polylactic acid in a preset ratio, irradiating with light for 0.5 to 1.5 hours, and then adding the mixture to a melt-blowing machine for melt-blowing treatment to obtain a graphene oxide grafted N-halamine melt-blown material;

[0043] S4, soaking the graphene oxide grafted N-halamine melt-blown material of step S3 in sodium hypochlorite for 0.5 to 1.0 h, washing, drying, and heat-treating to obtain the graphene oxide grafted N-halamine antibacterial melt-blown material; chlorinating the graphene oxide grafted N-halamine melt-blown material to achieve regeneration of antibacterial properties;

[0044] S5. Melt-spinning the graphene oxide grafted N-halamine antibacterial melt-blown material prepared in step S4 to obtain modified graphene polylactic acid antibacterial fiber.

[0045] In particular, the preparation method first combines an N-halamine precursor with graphene oxide by chemical bonding, and simultaneously adds a silane coupling agent containing a photosensitive thiol group to prevent the loss of the N-halamine precursor. The coupling agent can react with the graphene oxide, the N-halamine precursor, and the polylactic acid. Under light conditions, not only does the N-halamine precursor react again with the active groups on the surface of the graphene oxide through the silane coupling agent, but the photosensitive thiol groups on the graphene oxide are also combined with the unsaturated bonds in the polylactic acid by chemical bonding. This prevents the N-halamine from being separated from the graphene oxide-grafted N-halamine antibacterial material and the graphene oxide-grafted N-halamine antibacterial material from being lost on the antibacterial fiber, so that the prepared antibacterial fiber has good antibacterial effect and long antibacterial timeliness.

[0046] Specifically, in step S1, graphene oxide is prepared by a modified Hummers method, comprising the following steps:

[0047] SS1. Add a solid mixture of graphite powder and sodium nitrate to concentrated sulfuric acid in an ice-water bath under magnetic stirring, then slowly add potassium perchlorate and simultaneously add potassium permanganate in batches for reaction. The reaction temperature should not exceed 20°C and the mixture should be removed after 0.5 to 1.5 hours. The mass ratio of potassium perchlorate to potassium permanganate should be 5:3.

[0048] SS2. The solution treated in step SS1 was stirred at room temperature for 24 hours, diluted with 5% H2SO4 solution, stirred for 0.5 to 1.0 hours, and then H2O2 was added, stirred for 0.5 to 2.0 hours, and centrifuged to obtain a solid substance;

[0049] SS3. The solid material obtained in step SS2 is washed 1 to 3 times with a mixed solution of H2SO4, H2O2 and an HCl solution, respectively, and finally washed 1 to 3 times with distilled water to a pH value of 7. After drying, a yellow-brown precipitate is obtained, which is graphene oxide.

[0050] It should be noted that the lamellar graphene oxide used in the preparation method has a large specific surface area, contains a large number of surface active groups, and has a high grafting rate. The addition of a mercaptosilane coupling agent further increases the grafting rate of the graphene oxide, providing more reaction sites for N-halamine and coupling agents containing photosensitive mercapto groups. The presence of photosensitive mercapto groups on the graphene oxide surface enables the graphene oxide-grafted N-halamine antibacterial material to be stably bonded to the polylactic acid resin in a short period of time, improving the antibacterial properties and antibacterial load fastness of the resulting material. Furthermore, the lamellar graphene oxide has excellent electrical conductivity, and after melt blending with polylactic acid, it imparts antistatic properties. Furthermore, the lamellar graphene oxide exhibits anisotropy within the fiber, improving the strength of the antibacterial fiber and imparting excellent overall performance.

[0051] In step S2, the mercaptosilane coupling agent includes one of 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltrimethyloxysilane, 3-mercaptopropyltriphenylsilane, and 3-(methylpropoxy)propyltrimethoxysilane; the N-halamine precursor includes one of methacrylamide, 1-allylhydantoin, and 2,4-diamino-6-diallylamino-1,3,5-triazine; and the photoinitiator includes one of benzoin dimethyl ether, isopropylthioxanthone, and triaryl iodonium salt.

[0052] In some specific embodiments, in step S5, when the graphene oxide grafted N-halamine antibacterial melt-blown material is melt-spinned, deodorizing particles are added thereto and jointly participate in the melt spinning to obtain a modified graphene polylactic acid antibacterial fiber with a deodorizing function; the deodorizing particles include one or more of activated carbon particles, nanosilver particles, and active oxygen particles.

[0053] In some specific embodiments, in step S1, the alkaline solution is a sodium hydroxide solution.

[0054] A modified graphene polylactic acid antibacterial fiber is used to prepare antibacterial non-woven fabrics, and the antibacterial non-woven fabrics are used to prepare one or more antibacterial protective products such as medical masks, medical protective clothing and industrial clothing.

[0055] Example 1

[0056] This embodiment provides a method for preparing modified graphene polylactic acid antibacterial fiber, comprising the following steps:

[0057] S1. Preparation of lamellar graphene oxide using the improved Hummers method;

[0058] S11. Add a solid mixture of 2 g of graphite powder and 1 g of sodium nitrate to concentrated sulfuric acid in an ice-water bath under magnetic stirring, then slowly add 10 g of potassium perchlorate and simultaneously add 6 g of potassium permanganate in batches to react. The reaction temperature does not exceed 20° C. and the mixture is removed after 1.5 h.

[0059] S12, stirring the solution treated in step S11 at room temperature for 24 hours, and diluting it with a 5% H2SO4 solution. After stirring for 1 hour, 6 mL of H2O2 solution was added. The solution turned bright yellow. Stirring and reacting for 2 hours, the solution was centrifuged to obtain a solid substance.

[0060] S13. The solid material obtained in step S12 was washed twice with a mixed solution of H2SO4 and H2O2 and an HCl solution, and finally washed three times with distilled water to a pH value of 7. The solid material was fully dried in a vacuum drying oven at 40°C to obtain a yellow-brown precipitate, which is graphene oxide (GO).

[0061] S14, dispersing graphene oxide in deionized water, and ultrasonically exfoliating at 60W power for 3 hours to obtain graphene oxide colloid; adding an alkaline solution to the graphene oxide colloid, stirring at 95°C, and after the reaction is completed, washing, filtering, and drying in an oven at 40°C to obtain lamellar graphene oxide;

[0062] S2. The lamellar graphene oxide obtained in step S1 and 3-mercaptopropyltrimethoxysilane are added to anhydrous ethanol in a mass ratio of 5:100 to prepare a mixed solution, methacrylamide and a photoinitiator, benzoin dimethyl ether, are added to the mixed solution, and after irradiation for 1 hour, the mixture is centrifuged, washed, and vacuum-dried to obtain graphene oxide grafted N-halamine antibacterial powder; wherein the amount of methacrylamide added is 1% of the mass of the lamellar graphene oxide, the amount of the photoinitiator added is 0.5% of the mass of the lamellar graphene oxide, and the amount of 3-mercaptopropyltrimethoxysilane added is 3% of the mass of the polylactic acid;

[0063] S3, the graphene oxide grafted N-halamine antibacterial powder obtained in step S2 is mixed with polylactic acid (PLA) in a mass ratio of 9:1000, and after illumination for 1 hour, the mixture is added to a melt-blown machine for melt-blowing treatment to obtain a graphene oxide grafted N-halamine melt-blown material;

[0064] S4, soaking the graphene oxide grafted N-halamine melt-blown material in step S3 in sodium hypochlorite for 30 minutes, washing, drying, and heat-treating to obtain the graphene oxide grafted N-halamine antibacterial melt-blown material;

[0065] S5. Melt-spinning the graphene oxide grafted N-halamine antibacterial melt-blown material prepared in step S4 to obtain modified graphene polylactic acid antibacterial fiber.

[0066] See also Figure 2 The figure shows the molecular structure change process of the graphene oxide grafted N-halamine antibacterial powder prepared in this example. As can be seen from the figure, the molecular structure change process of the graphene oxide grafted N-halamine antibacterial powder is as follows: the first step is the reaction of graphene oxide with a mercaptosilane coupling agent to form a graphene oxide-silane coupling agent compound containing reactive functional groups; in the second step, the graphene oxide-mercaptosilane coupling agent compound reacts with the N-halamine through a nucleophilic substitution reaction to form the graphene oxide-grafted N-halamine compound.

[0067] See also Figure 3 The figure shows an electron microscope image of the modified graphene-polylactic acid antibacterial fiber prepared in Example 1. The figure shows that the protrusions on the surface of the polylactic acid-graphene oxide composite fiber indicate that graphene oxide has been mixed into the polylactic acid. These protrusions are formed by the dispersion and aggregation of graphene on the fiber surface. During the fiber preparation process, graphene oxide is often treated together with polylactic acid, and after heating and extrusion, a mixture is formed for fiberization. During this process, graphene interacts with polylactic acid molecules and may aggregate on the fiber surface to form protrusions. This structure can effectively enhance the physical bonding between graphene and polylactic acid, thereby improving the performance of the composite material. Therefore, the protrusion structure can be used to characterize the composite of graphene and polylactic acid.

[0068] Examples 2 to 4

[0069] Examples 2 to 4 provide a method for preparing a modified graphene polylactic acid antibacterial fiber. Compared with Example 1, the difference is that in Examples 2 to 4, the mass ratios of graphene oxide grafted N-halamine antibacterial powder and polylactic acid are 3:1000, 6:1000, and 12:1000, respectively; the rest are roughly the same as Example 1 and are not repeated here.

[0070] Comparative Example 1

[0071] Comparative Example 1 provides a method for preparing modified graphene polylactic acid antibacterial fiber. Compared with Example 1, the difference is that 3-mercaptopropyltrimethoxysilane and photoinitiator are not added in step S2, and light treatment is not performed. The rest is roughly the same as Example 1 and will not be repeated here.

[0072] Comparative Examples 2-3

[0073] Comparative Examples 2 to 3 provide a method for preparing modified graphene polylactic acid antibacterial fiber. Compared with Example 1, the difference is that in Comparative Examples 2 to 3, the mass ratios of graphene oxide grafted N-halamine antibacterial powder and polylactic acid are 1:1000 and 20:1000, respectively; the rest are roughly the same as Example 1 and will not be repeated here.

[0074] Comparative Example 4

[0075] Comparative Example 4 provides a method for preparing modified graphene polylactic acid antibacterial fiber. Compared with Example 1, the difference is that the chlorination treatment in step S4 is not performed; the rest is roughly the same as Example 1 and will not be repeated here.

[0076] Comparative Example 5

[0077] Comparative Example 5 provides a method for preparing modified graphene polylactic acid antibacterial fiber. Compared with Example 1, the difference is that step S1 is not performed, and nano-silica is used instead of lamellar graphene oxide in step S2; the rest is roughly the same as Example 1 and will not be repeated here.

[0078] The antibacterial properties and mechanical properties of the modified graphene polylactic acid antibacterial fibers prepared in Examples 1 to 4 and Comparative Examples 1 to 5 were tested, and the results are shown in the following table.

[0079] Table 1 Antibacterial fiber performance test results of Examples 1 to 4 and Comparative Examples 1 to 5

[0080]

[0081]

[0082] As shown in Table 1, antibacterial fibers prepared by mixing polylactic acid with a certain amount of graphene oxide-grafted N-halamine antibacterial powder exhibited excellent antibacterial properties. Examples 1 to 4 and Comparative Examples 2 and 3 show that the antibacterial properties of the polylactic acid composite fibers initially increased and then decreased with increasing content of the graphene oxide-grafted N-halamine antibacterial powder, indicating a threshold for the addition of graphene oxide-grafted N-halamine antibacterial powder. In Comparative Example 1, without the addition of a mercaptosilane coupling agent, the antibacterial properties of the fiber decreased compared to the previous example. This is because the graphene oxide-grafted N-halamine antibacterial powder aggregated within the fiber, affecting its antibacterial properties. Furthermore, without the addition of a mercaptosilane coupling agent, the graphene oxide-grafted N-halamine antibacterial material failed to chemically bond with the polylactic acid resin, affecting its strength. Furthermore, multiple chlorinations significantly reduced the antibacterial properties. In Comparative Example 4, the unchlorinated fiber exhibited reduced antimicrobial activity. This is because the graphene oxide-grafted N-halamine antimicrobial powder required chlorination to activate its functional groups, enhancing the composite fiber's antimicrobial capacity. In Comparative Example 5, where the graphene oxide was replaced with inorganic silica particles, the antimicrobial rate and strength of the composite fiber decreased. This was due to uneven dispersion of the inorganic particles within the fiber and the low adhesion between the antimicrobial powder and the resin matrix, which reduced its antimicrobial activity. This indicates that the mass ratio of the graphene oxide-grafted N-halamine antimicrobial powder to polylactic acid, the addition of a mercaptosilane coupling agent, and the structure of the inorganic particles all influence the fiber's antimicrobial and mechanical properties.

[0083] Examples 5-6

[0084] Examples 5 to 6 provide a method for preparing modified graphene polylactic acid antibacterial fiber. Compared with Example 1, the difference is that in Examples 5 to 6, the amount of mercaptosilane coupling agent added is 1% and 5% of the mass of polylactic acid. The rest is roughly the same as Example 1 and will not be repeated here.

[0085] Comparative Examples 6-7

[0086] Comparative Examples 6 to 7 provide a method for preparing modified graphene polylactic acid antibacterial fiber. Compared with Example 1, the difference is that in Examples 6 to 7, the amount of mercaptosilane coupling agent added is 0.5% and 7% of the mass of polylactic acid. The rest is roughly the same as Example 1 and will not be repeated here.

[0087] Comparative Examples 8-9

[0088] Comparative Examples 8 to 9 provide a method for preparing a modified graphene polylactic acid antibacterial fiber. Compared with Example 1, the difference is that the amount of N-halamine precursor added in Comparative Examples 8 to 9 is 0.1% and 2% of the mass of the lamellar graphene oxide, respectively. The rest is roughly the same as in Example 1 and will not be repeated here.

[0089] The antibacterial and mechanical properties of the modified graphene polylactic acid antibacterial fibers prepared in Examples 5 to 6 and Comparative Examples 6 to 9 were tested, and the results are shown in the following table.

[0090] Table 2 Antibacterial fiber performance test results of Examples 5 to 6 and Comparative Examples 6 to 9

[0091] Antibacterial rate (%) Antibacterial rate after 20 times of chlorination (%) Tensile strength (MPa) Example 5 99.9 95.6 58 Example 6 99.9 99.5 63 Comparative Example 6 99.9 94.8 56 Comparative Example 7 99.9 99.6 58 Comparative Example 8 96.7 95.4 56 Comparative Example 9 99.9 98.8 60

[0092] Table 2 shows that, generally speaking, the addition of an appropriate amount of N-halamine precursor can increase the tensile strength of PLA composites. However, the degree of improvement in tensile strength does not show a linear relationship with the N-halamine precursor content, but rather follows a saturation trend. Below a certain doping range, the tensile strength of PLA composites initially increases and then decreases with increasing N-halamine precursor content. Mercaptosilane coupling agents can be used to improve the bond strength between PLA and graphene oxide, thereby enhancing the mechanical properties and durability of the material. Furthermore, the amount of mercaptosilane coupling agent added to PLA affects its tensile strength. A mercaptosilane coupling agent dosage within the range of 1% to 5% by weight of the PLA significantly improves the material's tensile strength, resulting in superior mechanical properties. The appropriate addition of mercaptosilane coupling agent can significantly improve the bonding effect between polylactic acid and graphene oxide, thereby improving the mechanical properties and durability of polylactic acid materials, and further improving the tensile strength of polylactic acid, which is of great significance for the application of polylactic acid materials.

[0093] In summary, the present invention provides a modified graphene-polylactic acid antibacterial fiber, its preparation method, and application. The fiber uses polylactic acid as a fiber substrate, and the polylactic acid is uniformly loaded with a graphene oxide-grafted N-halamine antibacterial material. The graphene oxide-grafted N-halamine antibacterial material contains photosensitive thiol groups and is bonded to unsaturated bonds in the polylactic acid via the photosensitive thiol groups. In the preparation method of the present invention, a silane coupling agent containing a photosensitive thiol group is used to chemically bond the graphene oxide to the N-halamine precursor and the polylactic acid, respectively. This prevents the N-halamine from detaching from the graphene oxide-grafted N-halamine antibacterial material and preventing the graphene oxide-grafted N-halamine antibacterial material from escaping from the antibacterial fiber, resulting in a good antibacterial effect and long-lasting antibacterial effect. In addition, the selected lamellar graphene oxide provides more reaction sites, realizing the stable combination of the graphene oxide grafted N-halamine antibacterial material and the polylactic acid resin in a short time; it also has good electrical conductivity, and after melt blending with polylactic acid, it imparts antistatic function to the polylactic acid; and the lamellar graphene oxide has anisotropy in the fiber, which improves the strength of the antibacterial fiber, and when used in the preparation of antibacterial non-woven fabrics, it has good comprehensive performance; the antibacterial fiber and antibacterial non-woven fabric obtained by the present invention have both antibacterial properties, antistatic properties and strong mechanical properties, and have great market application value.

[0094] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A modified graphene polylactic acid antibacterial fiber, characterized in that: Polylactic acid is used as a fiber substrate, and a graphene oxide grafted N-halamine antibacterial material is uniformly loaded in the polylactic acid; the graphene oxide grafted N-halamine antibacterial material contains a photosensitive thiol group, and the graphene oxide grafted N-halamine antibacterial material is combined with the unsaturated bond in the polylactic acid through the photosensitive thiol group; the mass ratio of the polylactic acid to the graphene oxide grafted N-halamine antibacterial material is 1000:(3-15); the preparation method of the modified graphene polylactic acid antibacterial fiber comprises the following steps: S1. Dispersing graphene oxide in deionized water and ultrasonically exfoliating to obtain graphene oxide colloid; adding an alkaline solution to the graphene oxide colloid, stirring at 95-100° C., and after the reaction is completed, washing, filtering, and drying to obtain lamellar graphene oxide; S2. Adding the lamellar graphene oxide obtained in step S1 and a mercaptosilane coupling agent in proportion to anhydrous ethanol to prepare a mixed solution, adding an N-halamine precursor and a photoinitiator to the mixed solution, irradiating the solution for 1.0 to 2.0 hours, centrifuging, washing, and vacuum drying to obtain graphene oxide grafted N-halamine antibacterial powder; S3, mixing the graphene oxide grafted N-halamine antibacterial powder obtained in step S2 with polylactic acid in a preset ratio, irradiating with light for 0.5 to 1.5 hours, and then adding the mixture to a melt-blowing machine for melt-blowing treatment to obtain a graphene oxide grafted N-halamine melt-blown material; S4, soaking the graphene oxide grafted N-halamine melt-blown material in step S3 in sodium hypochlorite for 0.5 to 1.0 h, washing, drying, and heat-treating to obtain the graphene oxide grafted N-halamine antibacterial melt-blown material; S5. Melt-spinning the graphene oxide grafted N-halamine antibacterial melt-blown material prepared in step S4 to obtain the modified graphene polylactic acid antibacterial fiber.

2. The modified graphene polylactic acid antibacterial fiber according to claim 1, characterized in that: The mass ratio of the lamellar graphene oxide to the mercaptosilane coupling agent is (1-9):100; the added amount of the mercaptosilane coupling agent is 1%-5% of the mass of the polylactic acid.

3. The modified graphene polylactic acid antibacterial fiber according to claim 1, characterized in that: In step S2, the amount of the N-halamine precursor added is 0.5% to 1.5% of the mass of the flaky graphene oxide, and the amount of the photoinitiator added is 0.5% to 5.0% of the mass of the flaky graphene oxide.

4. The modified graphene polylactic acid antibacterial fiber according to claim 1, characterized in that: In step S5, during the melt spinning, deodorizing particles are added to the graphene oxide grafted N-halamine antibacterial melt-blown material, and the two materials participate in the melt spinning together to obtain a modified graphene polylactic acid antibacterial fiber with a deodorizing function; the deodorizing particles include one or more of activated carbon particles, nanosilver particles, and active oxygen particles.

5. The modified graphene polylactic acid antibacterial fiber according to claim 1, characterized in that: In step S1, the graphene oxide preparation comprises the following steps: SS1. Add the solid mixture of graphite powder and sodium nitrate to concentrated sulfuric acid in an ice-water bath under magnetic stirring, then slowly add potassium perchlorate and potassium permanganate in batches to react. The reaction temperature should not exceed 20°C and the mixture should be removed after 0.5 to 1.5 hours. SS2. The solution treated in step SS1 was stirred at room temperature for 24 hours, diluted with 5% H2SO4 solution, stirred for 0.5 to 1.0 hours, and then H2O2 was added, stirred for 0.5 to 2.0 hours, and centrifuged to obtain a solid substance; SS3. The solid material obtained in step SS2 is washed 1 to 3 times with a mixed solution of H2SO4, H2O2 and an HCl solution, respectively, and finally washed with distilled water 1 to 3 times to a pH value of 7. After drying, a yellow-brown precipitate is obtained, which is the graphene oxide.

6. The modified graphene polylactic acid antibacterial fiber according to claim 1, characterized in that: In step S2, the mercaptosilane coupling agent includes one of 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltrimethyloxysilane, 3-mercaptopropyltriphenylsilane, and 3-(methylpropoxy)propyltrimethoxysilane; the N-halamine precursor includes one of methacrylamide, 1-allylhydantoin, and 2,4-diamino-6-diallylamino-1,3,5-triazine.

7. The modified graphene polylactic acid antibacterial fiber according to claim 1, characterized in that: In step S2, the photoinitiator includes one of benzoin dimethyl ether, isopropylthioxanthone, and triaryl iodonium salt.

8. An application of modified graphene polylactic acid antibacterial fiber, characterized in that: The modified graphene polylactic acid antibacterial fiber is any one of claims 1 to 7, and the modified graphene polylactic acid antibacterial fiber is used to prepare antibacterial non-woven fabrics, and the antibacterial non-woven fabrics are used to prepare one or more antibacterial protective products such as medical masks, medical protective clothing and industrial clothing.

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