Flame-retardant and antibacterial dual-function fiber and preparation method thereof

Abstract

The invention relates to the technical field of polyester, in particular to a flame-retardant and antibacterial dual-function fiber and a preparation method thereof. The flame-retardant antibacterial fiber overcomes the defects that existing fibers are poor in flame retardance and antibacterial property. According to the invention, PET resin, a composite modified auxiliary agent master batch and a composite flexibilizer are used as raw materials, and the bifunctional fiber is prepared through melting and spinning; wherein the composite modified additive master batch is prepared from the following raw materials: PET (Polyethylene Terephthalate) resin, aluminum diethylphosphinate, modified halloysite nanotubes, modified zinc oxide nanowires and zinc borate; the modified halloysite nanotube is prepared from the following raw materials: a halloysite nanotube, KH560 and phosphoric acid; the modified zinc oxide nanowire is prepared from the following raw materials: zinc nitrate hexahydrate, hexamethylenetetramine and sodium hypophosphite. By controlling the dosage of each component and processing technological parameters, the finally prepared difunctional fiber has good flame retardance and good antibacterial property, and is suitable for manufacturing curtains.

Description

Technical Field

[0001] The present invention relates to the technical field of polyester fibers, and specifically to a fiber with dual functions of flame retardancy and antibacterial property and a preparation method thereof. Background Art

[0002] There are various types of polyester fibers. Common ones include polyethylene terephthalate fiber (PET, i.e., polyester), polytrimethylene terephthalate fiber (PTT), and polybutylene terephthalate fiber (PBT). In the home textile field, PTT fibers are often used to make high-grade bedding due to their soft handfeel, good resilience, and stain resistance, bringing a comfortable experience to users; PBT fibers are widely used in home textile fabrics such as curtains and sofa covers due to their high elasticity and low shrinkage rate, ensuring the lasting beauty and practicality of the fabrics; while polyester fibers have unique advantages in home textile applications. Compared with PTT fibers, their production cost is lower, enabling large-scale production and making home textile products more affordable; compared with PBT fibers, polyester fibers have higher strength and better wear resistance, being able to withstand frequent daily use and cleaning, and extending the service life of home textile products.

[0003] Polyester is widely used in the field of curtain making in home textiles. However, it also has obvious drawbacks in this field. In terms of flame retardancy, ordinary polyester fibers are easy to burn when encountering an open flame, and the burning speed is relatively fast, which poses a great safety hazard in the home environment. Once a fire occurs, the fire will spread rapidly. In terms of antibacterial property, polyester fibers are easily eroded by microorganisms such as bacteria and molds, resulting in the generation of odors, color changes, and even damage to the curtains, affecting their beauty and service life, and being unfavorable to indoor environmental hygiene. Therefore, it is urgent to develop a new type of polyester fiber with both strong flame retardancy and strong antibacterial property, which is of great significance for improving the safety and hygiene of curtain products and meeting the needs of consumers for high-quality home textile products.

[0004] For this reason, a fiber with dual functions of flame retardancy and antibacterial property and a preparation method thereof are proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide a fiber with dual functions of flame retardancy and antibacterial property and a preparation method thereof. The present invention uses PET resin, a composite modified additive masterbatch, and a composite toughening agent as raw materials to prepare a dual-functional fiber through melting and spinning; among them, the raw materials for preparing the composite modified additive masterbatch include PET resin, aluminum diethylphosphinate, modified halloysite nanotubes, modified zinc oxide nanowires, and zinc borate; the raw materials for preparing the modified halloysite nanotubes include halloysite nanotubes, KH560, and phosphoric acid; the raw materials for the modified zinc oxide nanowires include zinc nitrate hexahydrate, hexamethylenetetramine, and sodium hypophosphite. By controlling the dosages of each component and the processing process parameters, the finally prepared dual-functional fiber has good flame retardancy and good antibacterial property, and is suitable for the production of curtains.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] On the one hand, the present invention provides a fiber with flame retardant and antibacterial dual functions: by weight, it specifically includes the following components:

[0008] The fiber raw materials include 60-65 parts of PET resin, 15-20 parts of composite modified additive masterbatch, and 5-7 parts of composite toughening agent;

[0009] The composite modified additive masterbatch includes PET resin, aluminum diethylphosphinate, modified halloysite nanotubes, modified zinc oxide nanowires, and zinc borate;

[0010] The modified halloysite nanotubes include halloysite nanotubes, KH560, and phosphoric acid;

[0011] The modified zinc oxide nanowires include zinc nitrate hexahydrate, hexamethylenetetramine, and sodium hypophosphite;

[0012] The composite toughening agent includes ethylene-methyl acrylate-glycidyl methacrylate and maleic anhydride grafted ethylene-octene copolymer elastomer.

[0013] Preferably, the intrinsic viscosity of the PET resin is 0.65-0.67 dL / g.

[0014] Preferably, the length of the halloysite nanotubes is 0.2-1 μm; the length of the modified zinc oxide nanowires is 1-5 μm; the particle size of the zinc borate is 2-3 μm.

[0015] On the other hand, the present invention provides a preparation method of a fiber with flame retardant and antibacterial dual functions: the preparation method of the fiber with flame retardant and antibacterial dual functions is as follows:

[0016] S1 Mix the composite modified additive masterbatch, PET resin, and composite toughening agent and feed them into a twin-screw extruder, and obtain modified PET resin through melt extrusion and cooling pelletization;

[0017] S2 Dry the modified PET resin at 150 °C to reduce the moisture content to below 50 ppm;

[0018] S3 Melt the dried modified PET resin at 290 °C and extrude it through a spinneret to form a fine melt stream, and cure it under a cooling air flow at a temperature of 25 °C and a wind speed of 0.9 m / s to obtain nascent fibers;

[0019] S4 Draw the nascent fibers, with the first-stage drawing temperature being 85 °C and the second-stage drawing temperature being 150 °C, and the total draw ratio being 3.8-4.2 times;

[0020] S5 Wind the drawn fibers to obtain the fiber with flame retardant and antibacterial dual functions.

[0021] Preferably, the working temperatures of each zone in the melt extrusion step are 260°C, 275°C, 285°C, 290°C, 285°C respectively, and the screw speed is 60 - 70 rpm.

[0022] Preferably, the preparation method of the composite modified additive masterbatch is as follows: Mix 6 - 8 parts of aluminum diethylphosphinate, 0.4 - 0.6 parts of modified halloysite nanotubes, 1 - 1.2 parts of pretreated zinc borate, 0.6 - 0.8 parts of modified zinc oxide nanowires, antioxidant, lubricant and PET resin at a stirring speed of 1000 rpm for 10 min; Feed the mixed material into a twin - screw extruder for melt extrusion, and cool and pelletize to obtain the composite modified additive masterbatch; Among them, the working temperatures of each zone during melt extrusion are 240°C, 260°C, 270°C, 270°C, 265°C respectively, and the set screw speed is 120 - 130 rpm.

[0023] Preferably, when preparing the composite modified additive masterbatch, the screw speed in the melt extrusion step is 120 - 130 rpm.

[0024] Preferably, the preparation method of the modified halloysite nanotubes is as follows: By weight, disperse 10 parts of halloysite nanotubes in 100 parts of absolute ethanol to obtain suspension A; Add KH560 and deionized water to suspension A, the addition amount of KH560 is 8 - 10% of the weight of halloysite nanotubes, stir and react at 70°C for 4 - 5 h, then filter, wash and dry the solid to obtain epoxy - modified halloysite nanotubes; Disperse the epoxy - modified halloysite nanotubes in N,N - dimethylformamide to form suspension B; Then add 4.5 parts of phosphoric acid aqueous solution with a mass fraction of 75 - 85% to suspension B, stir and react at 70°C for 4.5 h, then filter, wash and dry the filtered solid to obtain modified halloysite nanotubes.

[0025] Preferably, the preparation method of the modified zinc oxide nanowires is as follows: By weight, dissolve 14 - 16 parts of zinc nitrate hexahydrate, 6 - 8 parts of hexamethylenetetramine and 0.1 - 0.15 parts of sodium hypophosphite in deionized water to obtain a precursor solution; React the precursor solution in a high - pressure reactor at 120°C for 7 - 9 h to obtain a reaction solution; After the reaction solution is cooled, centrifuge to obtain a precipitate; Wash and dry the precipitate to obtain phosphorus - containing zinc oxide nanowires; Add the phosphorus - containing zinc oxide nanowires to absolute ethanol, ultrasonically treat for 30 min to obtain a dispersion; Add KH550 accounting for 3 - 4% of the weight of the phosphorus - containing zinc oxide nanowires to the dispersion, stir and react at 60°C for 4 h, after the reaction is completed, filter, wash and dry the solid to obtain a crude powder, and grind the crude powder to obtain modified zinc oxide nanowires.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] 1. In the present invention, through the synergistic effect of aluminum diethylphosphinate, modified halloysite nanotubes, modified zinc oxide nanowires and pretreated zinc borate, high-efficiency flame retardancy and smoke suppression are achieved. This system combines multiple mechanisms such as gas-phase condensed-phase flame retardancy, nano physical barrier, phosphorus-silicon-zinc chemical synergistic enhancement of the carbon layer, and smoke suppression by the vitreous protective layer. Moreover, through the optimized dispersion process and the highly oriented structure of the fibers, the integrity of the carbon layer is further improved, thereby significantly increasing the limiting oxygen index and smoke density rating of the material.

[0028] 2. In the present invention, a compound toughening agent of ethylene-methyl acrylate-glycidyl methacrylate and maleic anhydride grafted ethylene-octene copolymer is used to construct a toughening phase with good interfacial bonding and highly dispersed through reactive compatibilization. This tough matrix effectively passivates the stress concentration of the internal solid fillers, enabling the fibers to withstand the draw ratio and draw temperature in this preparation system. Thus, while inducing a high degree of orientation of the polyester molecular chains to improve the breaking strength, good elongation at break is maintained, overcoming the problem of mechanical property loss in the high-filled system.

[0029] 3. In the present invention, modified zinc oxide nanowires are mainly used as the antibacterial core, and their antibacterial function is achieved by efficiently releasing zinc ions to destroy the bacterial structure. The realization of its excellent antibacterial effect lies in the synergistic effect of particle surface treatment, matrix compatibilization and multi-step precise control processing techniques including masterbatch predispersion, ensuring that the nano antibacterial agent reaches a uniform and fine dispersion state in the fiber matrix, especially in the near-surface region, thereby maximizing the exposure and activity of effective antibacterial sites.

[0030] 4. In the present invention, through a variety of material and process synergistic strategies such as surface modification of modified zinc oxide nanowires and zinc borate, addition of compound toughening agent, masterbatch predispersion, melt rheology control with the aid of lubricants, and thermal stability guaranteed by antioxidants, the interfacial compatibility and melt stability of the high-filled multi-component system are effectively improved. This significantly reduces the processing difficulty, realizes a stable melt blending and spinning process, makes the fiber sliver more uniform and the cross-section more regular, and improves the overall performance of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the antibacterial rate of Escherichia coli in Example 1, Example 4, Examples 6-7 and Comparative Examples 7-8 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in 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 fall within the protection scope of the present invention.

[0033] Please refer to Figure 1 , the present invention provides a fiber with flame retardant and antibacterial dual functions and a preparation method thereof, and the technical solutions are as follows:

[0034] Example 1

[0035] Preparation of modified halloysite nanotubes

[0036] Disperse 10 parts of halloysite nanotubes in 100 parts of absolute ethanol by ultrasonic for 30 min to obtain suspension A; add γ-glycidoxypropyltrimethoxysilane (KH560) and deionized water to suspension A. The addition amount of KH560 is 8% of the weight parts of halloysite nanotubes, and the addition amount of deionized water is 25% of the weight parts of KH560. Stir and react at 70 °C for 4 h and then filter. Wash and dry the solid for 12 h to obtain epoxy-modified halloysite nanotubes; disperse the epoxy-modified halloysite nanotubes in 500 parts of N,N-dimethylformamide to form suspension B, and then add 4.5 parts of phosphoric acid aqueous solution with a mass fraction of 75%. Stir and react at 70 °C for 4.5 h and then filter. Wash three times with N,N-dimethylformamide and then wash three times with deionized water. Finally, dry the washed solid product in an oven at 90 °C for 12 h to obtain modified halloysite nanotubes.

[0037] Preparation of modified zinc oxide nanowires

[0038] By weight, dissolve 14 parts of zinc nitrate hexahydrate, 6 parts of hexamethylenetetramine and 0.1 part of sodium hypophosphite in deionized water and make up the volume to 1 L to obtain a precursor solution; place the precursor solution in a high-pressure reaction kettle and react at 120 °C for 7 h to obtain a reaction solution; after the reaction solution cools, centrifuge to obtain a precipitate; wash and dry the precipitate in an oven at 70 °C for 12 h to obtain phosphorus-containing zinc oxide nanowires; add 0.6 part of phosphorus-containing zinc oxide nanowires to 30 parts of absolute ethanol and ultrasonically treat for 30 min to obtain a dispersion; add γ-aminopropyltriethoxysilane (KH550) which is 3% of the weight parts of phosphorus-containing zinc oxide nanowires to the dispersion, stir and react at 60 °C for 4 h. After the reaction is completed, filter, wash the solid with absolute ethanol and dry at 80 °C for 6 h to obtain a crude powder, and grind the crude powder to obtain modified zinc oxide nanowires.

[0039] The preparation method of the pretreated zinc borate is as follows: Add 1.5 parts of zinc borate into 30 parts of absolute ethanol, and perform ultrasonic treatment for 30 min to disperse. Then, add KH550, and the amount of KH550 is 3% of the weight of zinc borate. Stir the mixture at 60 °C for 4 h; after the reaction is completed, filter, wash the filtered solid with absolute ethanol 3 times, and dry to obtain the pretreated zinc borate.

[0040] Preparation of the composite modified additive masterbatch

[0041] Mix 6 parts of aluminum diethylphosphinate, 0.4 part of modified halloysite nanotubes, 1 part of pretreated zinc borate, 0.6 part of modified zinc oxide nanowires, 0.8 part of antioxidant, 0.4 part of lubricant, and 20 parts of PET resin at a stirring speed of 1000 rpm for 10 min; Feed the mixed material into a twin-screw extruder for melt extrusion and cooling pelletization to obtain the composite modified additive masterbatch; among them, the working temperatures of each zone during melt extrusion are 240 °C, 260 °C, 270 °C, 270 °C, and 265 °C respectively, and the screw speed is set at 120 rpm; The antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a weight ratio of 1:1; The lubricant is pentaerythritol tetrastearate.

[0042] Preparation of the flame-retardant and antibacterial bifunctional fiber

[0043] S1 Mix the composite modified additive masterbatch, PET resin, and composite toughening agent, and then feed them into a twin-screw extruder. After melt extrusion and cooling pelletization, obtain the modified PET resin; In the melt extrusion step, the working temperatures of each zone are 260 °C, 275 °C, 285 °C, 290 °C, and 285 °C respectively, and the screw speed is 60 rpm; In the composite toughening agent, ethylene-methyl acrylate-glycidyl methacrylate (Arkema, France, grade AX8900), maleic anhydride grafted ethylene-octene copolymer (Dongguan Taotao Plastic Raw Materials Co., Ltd., grade g-MAH);

[0044] S2 Dry the modified PET resin at 150 °C to reduce the moisture content to less than 50 ppm;

[0045] S3 Melt the dried modified PET resin at 290 °C and extrude it through a spinneret to form a fine melt stream, and solidify it under a cooling air flow at a temperature of 25 °C and a wind speed of 0.9 m / s to obtain the nascent fiber;

[0046] S4 Draw the nascent fiber, the first-stage drawing temperature is 85 °C and the second-stage drawing temperature is 150 °C, and the total draw ratio is 3.8 times;

[0047] S5 Wind the drawn fiber to obtain the flame-retardant and antibacterial bifunctional fiber.

[0048] The difference between Example 2 and Example 1 is as follows: The raw material composition of the flame-retardant and antibacterial bifunctional fiber includes 62.5 parts of PET resin, 17.5 parts of composite modified additive masterbatch, and 6 parts of composite toughening agent; in the preparation of modified halloysite nanotubes, the addition amount of KH560 is 9% of the weight of halloysite, the reaction time is 4.5 h, and the mass fraction of phosphoric acid is 80%.

[0049] The difference between Example 3 and Example 1 is as follows: The raw material composition of the flame-retardant and antibacterial bifunctional fiber includes 65 parts of PET resin, 20 parts of composite modified additive masterbatch, and 7 parts of composite toughening agent; in the preparation of modified halloysite nanotubes, the addition amount of KH560 is 10% of the weight of halloysite, the reaction time is 5 h, and the mass fraction of phosphoric acid is 85%.

[0050] The difference between Example 4 and Example 2 is as follows: The specific viscosity of the PET resin selected for the fiber is 0.66 dL / g; in the drawing step of fiber preparation, the total draw ratio is 4 times.

[0051] The difference between Example 5 and Example 2 is as follows: The specific viscosity of the PET resin selected for the fiber is 0.67 dL / g; in the drawing step of fiber preparation, the total draw ratio is 4.2 times.

[0052] The difference between Example 6 and Example 4 is as follows: When preparing modified zinc oxide nanowires, the raw materials include 15 parts of zinc nitrate hexahydrate, 7 parts of hexamethylenetetramine, 0.125 part of sodium hypophosphite, and the hydrothermal reaction time is 8 h; in the subsequent surface treatment, the addition amount of KH550 is 3.5% of the weight of phosphorus-containing zinc oxide nanowires.

[0053] The difference between Example 7 and Example 4 is as follows: When preparing modified zinc oxide nanowires, the raw materials include 16 parts of zinc nitrate hexahydrate, 8 parts of hexamethylenetetramine, 0.15 part of sodium hypophosphite, and the hydrothermal reaction time is 9 h; in the subsequent surface treatment, the addition amount of KH550 is 4% of the weight of phosphorus-containing zinc oxide nanowires.

[0054] The difference between Example 8 and Example 6 is as follows: In the melt extrusion step of modified PET resin, the screw speed is 65 rpm; in the preparation of composite modified additive masterbatch, the raw materials include 7 parts of aluminum diethylphosphinate, 0.5 part of modified halloysite nanotubes, 1.1 parts of pretreated zinc borate, 0.7 part of modified zinc oxide nanowires, and the screw speed during melt extrusion is 125 rpm.

[0055] The difference between Example 9 and Example 6 is as follows: In the melt extrusion step of modified PET resin, the screw speed is 70 rpm; in the preparation of composite modified additive masterbatch, the raw materials include 8 parts of aluminum diethylphosphinate, 0.6 part of modified halloysite nanotubes, 1.2 parts of pretreated zinc borate, 0.8 part of modified zinc oxide nanowires, and the screw speed during melt extrusion is 130 rpm.

[0056] The difference between Comparative Example 1 and Example 1 is only that: in the preparation process of the composite modified additive masterbatch, aluminum diethyl phosphinate, modified halloysite nanotubes, and modified zinc oxide nanowires are not added.

[0057] The difference between Comparative Example 2 and Example 1 is only that: in the preparation process of the composite modified additive masterbatch, zinc borate is not added.

[0058] The difference between Comparative Example 3 and Example 1 is only that: in the preparation process of the composite modified additive masterbatch, halloysite nanotubes are directly used to replace the modified halloysite nanotubes.

[0059] The difference between Comparative Example 4 and Example 1 is only that: in the preparation process of the composite modified additive masterbatch, commercially available zinc oxide nanowires (Guangzhou Hongwu Materials Technology Co., Ltd., CAS No. 1314-13-2) are directly used.

[0060] The difference between Comparative Example 5 and Example 1 is only that: in the preparation process of the composite modified additive masterbatch, the compound toughening agent is not added.

[0061] The difference between Comparative Example 6 and Example 1 is only that: in the preparation process of the composite modified additive masterbatch, ethylene-methyl acrylate-glycidyl methacrylate is used as the toughening agent, and maleic anhydride grafted ethylene-octene copolymer is not added.

[0062] The difference between Comparative Example 7 and Example 1 is only that: in the preparation process of the composite modified additive masterbatch, the modified zinc oxide nanowires are not added.

[0063] The difference between Comparative Example 8 and Example 1 is only that: in the preparation process of the modified zinc oxide nanowires, KH550 is not used for treatment.

[0064] The difference between Comparative Example 9 and Example 1 is only that: instead of preparing the composite modified additive masterbatch, all components in the composite modified additive masterbatch, including aluminum diethyl phosphinate, modified halloysite nanotubes, pretreated zinc borate, modified zinc oxide nanowires, antioxidant, and lubricant, are directly mixed with other PET resins and the composite toughening agent in the main extruder at one time.

[0065] The difference between Comparative Example 10 and Example 1 is only that: in the preparation process of the modified zinc oxide nanowires, KH550 is not used for treatment; at the same time, zinc borate is not surface-treated with KH550 either.

[0066] Test Example 1

[0067] Test objects: The polyester fibers prepared in Examples 1-3 and Comparative Examples 1-4, Comparative Example 7.

[0068] Test method: The limiting oxygen index of polyester fiber was tested according to GB / T2406.2-2009; the smoke density level of polyester fiber was tested according to GB / T8627-2007. The final test results are shown in Table 1.

[0069] Table 1 Flame retardant performance test results

[0070]

[0071]

[0072] As can be seen from Table 1, the overall ratio of fiber raw materials is linked to the preparation process of modified halloysite nanotubes to ensure that the flame retardant masterbatch reaches an effective concentration in the matrix. Aluminum diethylphosphinate, as the main phosphorus-based flame retardant, plays a fundamental role through gas-phase free radical quenching and condensed phase promotion of carbonization. Its efficiency is significantly enhanced by the introduced nano components: phosphoric acid functionalized halloysite nanotubes not only use their tubular structure to build a physical barrier to block heat and mass transfer, but also introduce phosphorus-silicon synergistic effects through surface-grafted phosphoric acid groups to enhance the stability and quality of the condensed phase carbon layer; at the same time, phosphorus-doped zinc oxide nanowires rely on their one-dimensional structure to physically enhance the carbon layer, and catalyze the carbonization process and supplement the gas-phase free radical capture capacity through the synergistic effect of phosphorus and zinc. This core flame retardant system further cooperates with the zinc borate present in the formula. Zinc borate promotes the formation of a dense glassy protective layer and effectively inhibits smoke generation, which together improves the limiting oxygen index and smoke density level performance of the material.

[0073] Comparative Examples 1 to 4 show the key influence of specific components and their modified states on the flame retardant and smoke suppression properties of fibers. Comparative Example 1 completely removes aluminum diethylphosphinate, modified halloysite nanotubes and modified zinc oxide nanowires in the core flame retardant system, and loses multiple mechanisms such as gas phase inhibition, condensed phase carbonization enhancement, physical barrier isolation, and phosphorus-silicon-zinc chemical synergy, resulting in the loss of flame retardant performance foundation, reduced limiting oxygen index and increased smoke density level. Comparative Example 2 lacks zinc borate, which destroys the smoke suppression mechanism of the glassy protective layer and reduces a flame retardant synergistic pathway, mainly causing an increase in smoke density and a decrease in the limiting oxygen index. Comparative Example 3 uses unmodified halloysite nanotubes, retains the physical barrier effect but lacks the phosphorus-silicon synergistic effect introduced by surface phosphoric acid functionalization, which reduces the stability of the carbon layer and weakens the flame retardant and smoke suppression effects. Comparative Example 4 uses commercially available zinc oxide nanowires that are not doped with phosphorus and whose surface properties are not optimized, and cannot achieve phosphorus-zinc synergistic catalytic carbonization, and poor dispersibility also weakens the role of its physical enhancement of the carbon layer, which also leads to a decrease in flame retardant performance. In Comparative Example 7, only the modified zinc oxide nanowires were removed, resulting in decreased structural integrity and weakened stability of the formed carbon layer.

[0074] These comparative examples together illustrate that the flame retardancy and smoke suppression effects of the present invention depend on the synergistic effect of four components: aluminum diethylphosphinate, halloysite nanotubes functionalized with phosphoric acid, modified zinc oxide nanowires doped with phosphorus, and zinc borate. The lack of any key component, such as Comparative Examples 1-2 and Comparative Example 7, or the state of the key component not meeting the requirements, such as using unmodified or undoped substitutes in Comparative Examples 3 and 4, will disrupt this precise synergistic mechanism, making it impossible to effectively establish or connect multiple flame retardant pathways, and affecting the quality and stability of the condensed-phase carbon layer and the gas-phase suppression effect. Ultimately, it is manifested as the deterioration of the limiting oxygen index and smoke density grade indicators.

[0075] Test Example 2

[0076] Test object: Test the polyester fibers in Examples 1-2, Examples 4-5, and Comparative Examples 5-6.

[0077] Test method: Refer to the test standard of GB / T14464-2017 to test the breaking strength and elongation at break of polyester fibers. The final test results are shown in Table 2.

[0078] Table 2 Test results of mechanical properties

[0079] Number Breaking strength (cN / dtex) Elongation at break (%) Example 1 4.64 76 Example 2 4.75 78 Example 4 4.90 80 Example 5 4.95 79 Comparative Example 5 3.98 55 Comparative Example 6 4.45 65

[0080] It can be seen from Table 2 that selecting PET resin within a specific viscosity range lays the foundation for fiber strength, and the subsequent drawing process, especially the setting of the total draw ratio, is the key process link to induce high molecular chain orientation and achieve high strength. The linkage of these two ensures that the potential of the matrix material can be transformed into excellent final fiber mechanical properties through optimizing the processing process.

[0081] Comparative Examples 5 and 6 mainly verify the importance of the compound toughening agent system in improving the mechanical properties of highly filled fibers. In Comparative Example 5, no toughening agent is added at all, making the polyester matrix extremely brittle and hard in the presence of a large amount of solid fillers. The filler particles become serious stress concentration sources, resulting in the material being extremely prone to brittle fracture under external force, with a sharp decrease in elongation at break and a decrease in breaking strength due to the inability to effectively transfer stress. In Comparative Example 6, only a single-component ethylene-methyl acrylate-glycidyl methacrylate is used as the toughening agent, lacking the maleic anhydride grafted ethylene-octene copolymer elastomer and its reactive compatibilization synergistic effect with the former. This leads to the dispersion uniformity of the toughening phase and the interfacial bonding force with the matrix being inferior to those of the compound system, weakening the ability to passivate the stress concentration of the filler, limiting the toughness of the matrix, and ultimately showing an elongation at break lower than that of the examples using the compound toughening agent, while also limiting the potential of the fiber to reach the optimal strength under high magnification stretching.

[0082] These two comparative examples jointly verify the necessity of using a compound toughening agent and constructing a strong and tough matrix through reactive compatibilization in the present invention. Comparative example 5 shows that toughening is a prerequisite for maintaining basic mechanical properties in a highly filled system; comparative example 6 further proves that the specific compound system selected in the present invention can more effectively improve the interfacial compatibility, dispersion morphology and stress transfer through the synergistic effect at the molecular level compared with a single toughening agent, thus providing a key material basis for subsequently improving the strength and maintaining good elongation by optimizing the stretching process. Without this synergistic toughening, even with the same stretching treatment, it is difficult to achieve the ideal level of mechanical properties, indicating the importance of the synergy between material composition and processing technology for mechanical properties.

[0083] Test example 3

[0084] Test object: The fabrics prepared from the polyester fibers in Examples 1, 4, 6 - 7 and Comparative Examples 7 - 8 were tested after being washed 10 times.

[0085] Test method: Refer to GB / T20944.3 - 2008 "Evaluation of antibacterial properties of textiles - Part 3: Oscillation method", and Escherichia coli was selected as the strain. The final test results are shown in Table 3 and Figure 1 as follows.

[0086] Table 3 Test results of antibacterial properties

[0087] Number Antibacterial rate against Escherichia coli (%) Example 1 90.7 Example 4 92.3 Example 6 93.5 Example 7 93.8 Comparative Example 7 65.8 Comparative Example 8 86.4

[0088] Table 3 and Figure 1 It can be seen that the preparation process of the modified zinc oxide nanowires, including specific hydrothermal reaction conditions and subsequent surface treatment, determines the morphology, doping state and surface properties of the antibacterial core substance. The nanowires prepared by parameter control cooperate with the matrix environment to ensure the effective release of antibacterial ions and the long-term exertion of functions, realizing the antibacterial properties of the fibers.

[0089] Comparative Examples 7 and 8 mainly investigate the effects of modified zinc oxide nanowires and their surface treatment on the antibacterial properties of fibers. Comparative Example 7 directly removes the modified zinc oxide nanowires as the antibacterial core, causing the fiber to lose its main source of antibacterial activity. According to the principles of the present invention, even if zinc borate containing zinc is present in the formula, its zinc ion release efficiency is much lower than that of the specially designed nanowires, and it cannot provide effective antibacterial protection, especially after washing, the antibacterial rate will be extremely low. Although comparative example 8 uses phosphorus-containing zinc oxide nanowires, the subsequent KH550 surface treatment step is omitted. According to the analysis of the present invention, the surface treatment is intended to improve the compatibility of nanowires with the hydrophobic polyester matrix, promote uniform dispersion and enhance interfacial bonding. The lack of surface treatment will cause nanowires to agglomerate, reduce the exposed effective antibacterial sites, and more importantly, the weak interfacial bonding force makes the nanowires easy to fall off during washing or use, resulting in a decrease in the durability of the antibacterial effect and a significant decrease in the antibacterial rate after washing.

[0090] These two comparative examples confirm the source of the antibacterial properties of the present invention and the conditions for achieving them from both positive and negative aspects. Comparative Example 7 proves that modified zinc oxide nanowires are an indispensable core component for achieving antibacterial functions. Comparative Example 8 emphasizes that it is not enough to simply introduce antibacterial substances. It is necessary to use auxiliary means such as surface treatment, combined with matrix volume expansion and precision processing to ensure that the antibacterial agent is stably present and effectively distributed in the fiber in order to obtain excellent and lasting antibacterial effects. This reflects that the synergistic effect of material selection, surface science and processing technology in achieving functionality is crucial to the final antibacterial performance.

[0091] Test Example 4

[0092] Test object: The polyester fibers prepared in Example 1, Example 6, Examples 8-9 and Comparative Examples 9-10 were tested.

[0093] Test method: Refer to test example 1-3 for the test method.

[0094] The final test results are shown in Table 4.

[0095] Table 4 Comprehensive performance test results

[0096]

[0097] As can be seen in Table 4, controlling the size of halloysite, zinc oxide nanowires and zinc borate, in conjunction with setting the screw speed in the main extrusion and masterbatch extrusion processes, optimizes melt fluidity and shear dispersion. The combination of precise particle size control and appropriate processing shear force effectively improves the dispersion uniformity of the highly filled system, thereby ensuring a stable processing process and uniformity of the final fiber.

[0098] Comparative Examples 9 and 10 focus on verifying the decisive role of the preparation process, especially the pre-dispersion of masterbatch and the surface treatment of particles, on the processing stability of highly filled complex systems and the uniformity of the final product. Comparative Example 9 uses a one-time blending to replace the masterbatch pre-dispersion process. Due to the limited mixing time and shear strength of the main extruder, it is not enough to effectively break up the high-content, multi-type nano-micro filler agglomerates, resulting in extremely uneven material dispersion. This unevenness directly causes problems such as melt viscosity fluctuations, unstable processing pressure, and easy clogging of the mold, making it difficult to carry out the spinning process stably, and the final fiber has poor dryness, inconsistent performance, and a comprehensive decline in comprehensive performance. Comparative Example 10 also omits the surface treatment of zinc oxide nanowires and zinc borate, two inorganic fillers. This makes the interface compatibility between the filler and the organic matrix extremely poor, which not only exacerbates the problem of filler agglomeration, but also forms a large number of weak interfaces. These factors work together to further deteriorate the melt rheology and processing stability, and seriously damage the mechanical properties, flame retardancy and antibacterial properties of the final fiber, resulting in deterioration of comprehensive performance.

[0099] Comparative Example 9 shows that masterbatch pre-dispersion overcomes the dispersion problem in the preparation of highly filled nanocomposites and ensures the uniform dispersion of materials. Comparative Example 10 emphasizes that particle surface modification is indispensable in improving the interfacial compatibility between inorganic fillers and organic matrices, stabilizing the processing process, and ensuring the final material performance. In general, the synergy of particle surface treatment, compound toughening, masterbatch pre-dispersion, additive matching, and precise process control effectively solves the processing problem of highly filled complex systems and achieves the unity of function, performance, and manufacturability.

[0100] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A flame retardant and antibacterial dual-functional fiber, characterized by: By weight, it specifically includes the following components: The fiber raw material includes 60-65 parts of PET resin, 15-20 parts of composite modification auxiliary agent masterbatch, and 5-7 parts of composite toughening agent; The composite modified auxiliary agent masterbatch comprises the PET resin, aluminum diethylphosphinate, modified halloysite nanotubes, modified zinc oxide nanowires, and zinc borate; The modified halloysite nanotubes include halloysite nanotubes, KH560, and phosphoric acid; The modified zinc oxide nanowires include zinc nitrate hexahydrate, hexamethylenetetramine, and sodium hypophosphite; The composite toughening agent comprises ethylene-methyl acrylate-glycidyl methacrylate and maleic anhydride grafted ethylene-octene copolymer elastomer.

2. The flame retardant and antibacterial dual-functional fiber according to claim 1, characterized in that: The specific viscosity of the PET resin is 0.65-0.67 dL / g.

3. A method for preparing the flame-retardant and antibacterial dual-functional fiber as claimed in claim 1, characterized in that: The preparation method of the flame retardant and antibacterial dual-functional fiber is as follows: S1: Mixing the composite modification agent masterbatch, PET resin and composite toughening agent, and feeding them into a twin-screw extruder, and obtaining modified PET resin by melt extrusion, cooling and pelletizing; S2 drying the modified PET resin at 150° C. to reduce the moisture content to below 50 ppm; S3: melting the dried modified PET resin at 290° C., extruding it through a spinneret to form a thin melt stream, and solidifying it in a cooling airflow at a temperature of 25° C. and a wind speed of 0.9 m / s to obtain a nascent fiber; S4: drawing the spun fiber, wherein the first-stage drawing temperature is 85° C. and the second-stage drawing temperature is 150° C., and the total drawing multiple is 3.8-4.2 times; S5 winds the stretched fiber to obtain the flame-retardant and antibacterial dual-functional fiber.

4. The method for preparing the flame-retardant and antibacterial dual-functional fiber according to claim 3, characterized in that: The screw speed in the melt extrusion step is 60-70 rpm.

5. The method for preparing the flame-retardant and antibacterial dual-functional fiber according to claim 3, characterized in that: The preparation method of the composite modified additive masterbatch is as follows: 6-8 parts of diethyl aluminum phosphinate, 0.4-0.6 parts of modified halloysite nanotubes, 1-1.2 parts of pretreated zinc borate, 0.6-0.8 parts of modified zinc oxide nanowires, an antioxidant, a lubricant and the PET resin are stirred and mixed at a speed of 1000 rpm for 10 minutes; the mixture is fed into a twin-screw extruder for melt extrusion, and the mixture is cooled and pelletized to obtain the composite modified additive masterbatch.

6. The method for preparing the flame-retardant and antibacterial dual-functional fiber according to claim 5, characterized in that: When the composite modified auxiliary agent masterbatch is prepared, the screw speed in the melt extrusion step is 120-130 rpm.

7. The method for preparing the flame-retardant and antibacterial dual-functional fiber according to claim 5, characterized in that: The preparation method of the modified halloysite nanotubes is as follows: by weight, 10 parts of halloysite nanotubes are ultrasonically dispersed in 100 parts of anhydrous ethanol to obtain a suspension A; KH560 and deionized water are added to the suspension, wherein the amount of KH560 added is 8-10% of the weight of the halloysite nanotubes, the mixture is stirred at 70°C for reaction for 4-5 hours, and then filtered, and the solid is washed and dried to obtain epoxy-modified halloysite nanotubes; the epoxy-modified halloysite nanotubes are dispersed in N,N-dimethylformamide to form a suspension B; 4.5 parts of a phosphoric acid aqueous solution with a mass fraction of 75-85% are added to the suspension B, the mixture is stirred at 70°C for reaction for 4.5 hours, and then filtered, and the filtered solid is washed and dried to obtain the modified halloysite nanotubes.

8. The method for preparing the flame-retardant and antibacterial dual-functional fiber according to claim 5, characterized in that: The preparation method of the modified zinc oxide nanowires is as follows: by weight, 14-16 parts of zinc nitrate hexahydrate, 6-8 parts of hexamethylenetetramine and 0.1-0.15 parts of sodium hypophosphite are dissolved in deionized water to obtain a precursor solution; the precursor solution is reacted in a high-pressure reactor at 120° C. for 7-9 hours to obtain a reaction solution; the reaction solution is cooled and centrifuged to obtain a precipitate; the precipitate is washed and dried to obtain phosphorus-containing zinc oxide nanowires; the phosphorus-containing zinc oxide nanowires are added to anhydrous ethanol and subjected to ultrasonic treatment for 30 minutes to obtain a dispersion; Add 3-4% KH550 by weight of phosphorus-containing zinc oxide nanowires to the dispersion, stir and react at 60° C. for 4 hours, filter after the reaction is completed, wash and dry the solid to obtain a coarse powder; grind the coarse powder to obtain the modified zinc oxide nanowires.

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