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

Abstract

The present invention relates to the field of polyester technology, and specifically to a flame-retardant and antibacterial dual-functional fiber and a preparation method thereof. The present invention overcomes the shortcomings of existing fibers, namely, poor flame retardancy and poor antibacterial properties. The present invention uses PET resin, composite modified auxiliary agent masterbatch, and composite toughening agent as raw materials to prepare dual-functional fibers through melting and spinning; wherein, the raw materials for preparing the composite modified auxiliary agent 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 preparing the modified zinc oxide nanowires include zinc nitrate hexahydrate, hexamethylenetetramine, and sodium hypophosphite. By controlling the amount of each component and the processing parameters, the present invention finally prepares a dual-functional fiber with good flame retardancy and good antibacterial properties, and is suitable for use in the production of curtains.

Description

Technical Field

[0001] The present invention relates to the technical field of polyester, in particular to a flame-retardant and antibacterial dual-functional fiber and a preparation method thereof. Background Art

[0002] There are many types of polyester fibers, the most common of which are polyethylene terephthalate (PET, also known as polyester), polytrimethylene terephthalate (PTT), and polybutylene terephthalate (PBT). In the home textile field, PTT fiber is often used to make high-end bedding due to its soft feel, good resilience, and stain resistance, which can bring a comfortable experience to users. PBT fiber is widely used in home textile fabrics such as curtains and sofa covers due to its high elasticity and low shrinkage rate, which can ensure the long-lasting beauty and practicality of the fabric. Polyester fiber has unique advantages in home textile applications. Compared with PTT fiber, its production cost is lower and it can be produced on a large scale, making home textile products more affordable. Compared with PBT fiber, polyester fiber is stronger and more wear-resistant, and can withstand frequent daily use and cleaning, extending the service life of home textile products.

[0003] Polyester is widely used in the production of curtains for home textiles, but it also has significant shortcomings in this area. In terms of flame retardancy, ordinary polyester fibers easily burn when exposed to open flames, and the burning rate is relatively high. This poses a significant safety hazard in the home environment. Once a fire occurs, the fire will spread rapidly. In terms of antibacterial properties, polyester fibers are easily corroded by microorganisms such as bacteria and mold, causing curtains to develop odors, discolor, and even damage, affecting their aesthetics and service life, and also detrimental to indoor environmental hygiene. Therefore, the development of a new polyester fiber with both strong flame retardancy and strong antibacterial properties is urgent. This is of great significance for improving the safety and hygiene of curtain products and meeting consumer demand for high-quality home textile products.

[0004] Therefore, a flame-retardant and antibacterial dual-functional fiber and a preparation method thereof are proposed. Summary of the Invention

[0005] The present invention aims to provide a flame-retardant and antibacterial dual-functional fiber and its preparation method. The present invention uses PET resin, a composite modified additive masterbatch, and a composite toughening agent as raw materials through melt spinning to produce the dual-functional fiber. The composite modified additive masterbatch is made from PET resin, aluminum diethylphosphinate, modified halloysite nanotubes, modified zinc oxide nanowires, and zinc borate; the modified halloysite nanotubes are made from halloysite nanotubes, KH560, and phosphoric acid; and the modified zinc oxide nanowires are made from zinc nitrate hexahydrate, hexamethylenetetramine, and sodium hypophosphite. By controlling the amounts of the various components and the processing parameters, the dual-functional fiber produced has excellent flame retardancy and antibacterial properties, making it suitable for use in curtain production.

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

[0007] In one aspect, the present invention provides a flame-retardant and antibacterial dual-functional fiber, which specifically comprises the following components in parts by weight:

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

[0009] 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 specific 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; and the particle size of the zinc borate is 2-3 μm.

[0015] On the other hand, the present invention provides a method for preparing flame-retardant and antibacterial dual-functional fibers: The method for preparing flame-retardant and antibacterial dual-functional fibers is as follows:

[0016] S1: Mixing the composite modifying agent masterbatch, PET resin, and composite toughening agent, and then feeding them into a twin-screw extruder, and then melting, extruding, cooling, and pelletizing to obtain modified PET resin;

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

[0018] In step S3, the dried modified PET resin is melted at 290°C and extruded through a spinneret to form a thin melt stream, which is then solidified in a cooling air flow at a temperature of 25°C and a wind speed of 0.9 m / s to obtain spun fibers.

[0019] S4 draws the spun fiber, with the first-stage drawing temperature at 85°C and the second-stage drawing temperature at 150°C, and the total drawing ratio is 3.8-4.2 times;

[0020] S5 winds the drawn fibers to obtain flame-retardant and antibacterial dual-functional fibers.

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

[0022] Preferably, the preparation method of the composite modification additive masterbatch is: 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, antioxidants, lubricants and 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 cooled and pelletized to obtain the composite modification additive masterbatch; wherein, 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 to 120-130 rpm.

[0023] Preferably, when preparing the composite modifying auxiliary agent 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: 10 parts by weight 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, the amount of KH560 added is 8-10% by weight of the halloysite nanotubes, the reaction is stirred at 70°C for 4-5 hours, and then filtered, 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 75-85% by mass phosphoric acid aqueous solution are added to the suspension B, the reaction is stirred at 70°C for 4.5 hours, and then filtered, the filtered solid is washed and dried to obtain modified halloysite nanotubes.

[0025] Preferably, the preparation method of the modified zinc oxide nanowires is as follows: 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 by weight 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 ultrasonically treated for 30 minutes to obtain a dispersion; 3-4% KH550 by weight of the phosphorus-containing zinc oxide nanowires is added to the dispersion, and the mixture is stirred and reacted at 60° C. for 4 hours. After the reaction is completed, the mixture is filtered, the solid is washed and dried to obtain a coarse powder, and the coarse powder is ground to obtain modified zinc oxide nanowires.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. This invention achieves highly effective flame retardancy and smoke suppression through the synergistic effects of aluminum diethylphosphinate, modified halloysite nanotubes, modified zinc oxide nanowires, and pretreated zinc borate. This system combines multiple mechanisms: vapor-phase condensed-phase flame retardancy, nanoscale physical barriers, a chemically reinforced carbon layer of phosphorus, silicon, and zinc, and a glassy protective layer for smoke suppression. The integrity of the carbon layer is further enhanced through an optimized dispersion process and a highly oriented fiber structure, significantly improving the limiting oxygen index and smoke density rating of the material.

[0028] 2. The present invention utilizes a composite toughening agent consisting of ethylene-methyl acrylate-glycidyl methacrylate and maleic anhydride-grafted ethylene-octene copolymer. Through reactive compatibilization, a highly dispersed toughening phase with good interfacial bonding is constructed. This strong matrix effectively neutralizes stress concentration within the solid filler, enabling the fiber to withstand the draw ratios and temperatures of this preparation system. This results in a high degree of orientation of the polyester molecular chains, enhancing breaking strength while maintaining good elongation at break, overcoming the problem of mechanical property loss associated with highly filled systems.

[0029] 3. This invention primarily utilizes modified zinc oxide nanowires as the antibacterial core, achieving antibacterial function through their efficient release of zinc ions, which destroy bacterial structures. The key to achieving this excellent antibacterial effect lies in the synergistic effect of a multi-step, precision-controlled processing process, including particle surface treatment, matrix expansion, and masterbatch pre-dispersion. This ensures a uniform and fine dispersion of the nano-antimicrobial agent within the fiber matrix, particularly near the surface, thereby maximizing the exposure and activity of effective antimicrobial sites.

[0030] 4. This invention effectively improves the interfacial compatibility and melt stability of a highly filled, multi-component system through a multi-faceted material and process synergy strategy, including surface modification of modified zinc oxide nanowires and zinc borate, addition of a composite toughening agent, pre-dispersion of masterbatches, melt rheology control with lubricants, and thermal stability guaranteed by antioxidants. This significantly reduces processing difficulty, enables a stable melt blending and spinning process, and results in more uniform fiber strands and a more regular cross-section, enhancing the overall performance of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This 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

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0033] See also Figure 1 The present invention provides a flame-retardant and antibacterial dual-functional fiber and a preparation method thereof. The technical solution is as follows:

[0034] Example 1

[0035] Preparation of modified halloysite nanotubes

[0036] Ten parts of halloysite nanotubes were ultrasonically dispersed in 100 parts of anhydrous ethanol for 30 minutes to obtain suspension A. γ-glycidoxypropyltrimethoxysilane (KH560) and deionized water were added to the suspension, with the KH560 added at 8% of the weight of the halloysite nanotubes and the deionized water added at 25% of the weight of the KH560. The mixture was stirred at 70°C for 4 hours, filtered, and the solid was washed and dried for 12 hours to obtain epoxy-modified halloysite nanotubes. The epoxy-modified halloysite nanotubes were dispersed in 500 parts of N,N-dimethylformamide to form suspension B. 4.5 parts of a 75% aqueous phosphoric acid solution were added, stirred at 70°C for 4.5 hours, filtered, washed three times with N,N-dimethylformamide, and then washed three times with deionized water. Finally, the washed solid product was dried in a 90°C oven for 12 hours to obtain modified halloysite nanotubes.

[0037] Preparation of modified zinc oxide nanowires

[0038] The invention discloses a method for preparing a zinc oxide nanowire by preparing a method of preparing a zinc oxide nanowire. The method comprises the following steps: dissolving 14 parts of zinc nitrate hexahydrate, 6 parts of hexamethylenetetramine and 0.1 parts of sodium hypophosphite in deionized water and adjusting the volume to 1 L to obtain a precursor solution; reacting the precursor solution in a high-pressure reactor at 120° C. for 7 hours to obtain a reaction solution; cooling the reaction solution and centrifuging to obtain a precipitate; washing the precipitate and drying it in an oven at 70° C. for 12 hours to obtain phosphorus-containing zinc oxide nanowires; adding 0.6 parts of phosphorus-containing zinc oxide nanowires to 30 parts of anhydrous ethanol and ultrasonically treating the mixture for 30 minutes to obtain a dispersion; adding 3% of γ-aminopropyltriethoxysilane (KH550) by weight of the phosphorus-containing zinc oxide nanowires to the dispersion, stirring and reacting the mixture at 60° C. for 4 hours, filtering the mixture after the reaction is completed, washing the solid with anhydrous ethanol, and drying the mixture at 80° C. for 6 hours to obtain a coarse powder, and grinding the coarse powder to obtain modified zinc oxide nanowires.

[0039] The pretreated zinc borate is prepared by adding 1.5 parts of zinc borate to 30 parts of anhydrous ethanol and sonicating for 30 minutes to disperse the mixture. KH550 is then added at a concentration of 3% by weight relative to the zinc borate. The mixture is stirred and reacted at 60°C for 4 hours. After the reaction is complete, the mixture is filtered, the filtered solid is washed three times with anhydrous ethanol, and dried to obtain the pretreated zinc borate.

[0040] Preparation of composite modified additive masterbatch

[0041] 6 parts of aluminum diethylphosphinate, 0.4 parts of modified halloysite nanotubes, 1 part of pretreated zinc borate, 0.6 parts of modified zinc oxide nanowires, 0.8 parts of antioxidant, 0.4 parts of lubricant and 20 parts of PET resin were stirred and mixed at a speed of 1000 rpm for 10 minutes; the mixture was fed into a twin-screw extruder for melt extrusion, cooled and pelletized to obtain a composite modified additive masterbatch; wherein, the working temperatures of each zone during melt extrusion were 240°C, 260°C, 270°C, 270°C and 265°C, respectively, and the screw speed was set to 120 rpm; the antioxidant was a mixture of antioxidant 1010 and antioxidant 168 in a weight ratio of 1:1; and the lubricant was pentaerythritol tetrastearate.

[0042] Preparation of flame-retardant and antibacterial dual-functional fibers

[0043] S1: A composite modifying agent masterbatch, PET resin, and a composite toughening agent are mixed and fed into a twin-screw extruder, melt-extruded, cooled, and pelletized to obtain a modified PET resin. The operating temperatures of the various zones in the melt extrusion step are 260° C., 275° C., 285° C., 290° C., and 285° C., respectively, and the screw speed is 60 rpm. The composite toughening agent comprises ethylene-methyl acrylate-glycidyl methacrylate (Arkema, France, brand AX8900) and maleic anhydride-grafted ethylene-octene copolymer (Dongguan Taotao Plastic Materials Co., Ltd., brand g-MAH).

[0044] S2 dries the modified PET resin at 150°C to reduce the moisture content to below 50 ppm;

[0045] In step S3, the dried modified PET resin is melted at 290°C and extruded through a spinneret to form a thin melt stream, which is then solidified in a cooling air flow at a temperature of 25°C and a wind speed of 0.9 m / s to obtain spun fibers.

[0046] S4 draws the spun fiber, with the first-stage drawing temperature at 85°C and the second-stage drawing temperature at 150°C, and the total drawing ratio is 3.8 times;

[0047] S5 winds the drawn fibers to obtain flame-retardant and antibacterial dual-functional fibers.

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

[0049] The difference between Example 3 and Example 1 is that the raw material composition of the flame retardant and antibacterial dual-functional fiber includes 65 parts of PET resin, 20 parts of composite modification auxiliary agent masterbatch, and 7 parts of composite toughening agent; in the preparation of modified halloysite nanotubes, the amount of KH560 added is 10% of the weight of halloysite, the reaction time is 5 hours, and the mass fraction of phosphoric acid is 85%.

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

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

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

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

[0054] The difference between Example 8 and Example 6 is that the screw speed in the melt extrusion step of the modified PET resin is 65 rpm; the raw materials in the preparation of the composite modification additive masterbatch include 7 parts of diethyl aluminum phosphinate, 0.5 parts of modified halloysite nanotubes, 1.1 parts of pretreated zinc borate, and 0.7 parts 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 that the screw speed in the melt extrusion step of the modified PET resin is 70 rpm; the raw materials in the preparation of the composite modification additive masterbatch include 8 parts of diethyl aluminum phosphinate, 0.6 parts of modified halloysite nanotubes, 1.2 parts of pretreated zinc borate, and 0.8 parts of modified zinc oxide nanowires, and the screw speed during melt extrusion is 130 rpm.

[0056] The only difference between Comparative Example 1 and Example 1 is that during the preparation of the composite modification additive masterbatch, aluminum diethylphosphinate, modified halloysite nanotubes, and modified zinc oxide nanowires are not added.

[0057] The only difference between Comparative Example 2 and Example 1 is that zinc borate is not added during the preparation of the composite modification additive masterbatch.

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

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

[0060] The only difference between Comparative Example 5 and Example 1 is that no compound toughening agent is added during the preparation of the composite modification auxiliary agent masterbatch.

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

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

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

[0064] The only difference between Comparative Example 9 and Example 1 is that no composite modification additive masterbatch is prepared. Instead, all components of the composite modification additive masterbatch, including aluminum diethylphosphinate, modified halloysite nanotubes, pretreated zinc borate, modified zinc oxide nanowires, antioxidant, and lubricant, are directly mixed with other PET resins and composite toughening agents in the main extruder at one time.

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

[0066] Test Example 1

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

[0068] Test Method: The limiting oxygen index of polyester fiber was tested according to GB / T2406.2-2009; the smoke density grade 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 shown in Table 1, the overall fiber raw material ratio is linked to the preparation process of the modified halloysite nanotubes, ensuring an effective flame-retardant masterbatch concentration within the matrix. Aluminum diethylphosphinate, the primary phosphorus-based flame retardant, plays a fundamental role by quenching gas-phase free radicals and promoting condensed-phase carbonization. Its effectiveness is significantly enhanced by the introduction of additional nanocomposites: Phosphoric acid-functionalized halloysite nanotubes not only create a physical barrier to heat and mass transfer through their tubular structure, but also enhance the stability and quality of the condensed-phase carbon layer through a phosphorus-silicon synergistic effect introduced by surface-grafted phosphoric acid groups. Simultaneously, phosphorus-doped zinc oxide nanowires physically reinforce the carbon layer with their one-dimensional structure, catalyzing the carbonization process and supplementing the gas-phase free radical capture capacity through a synergistic interaction between phosphorus and zinc. This core flame-retardant system further synergizes with the presence of zinc borate in the formulation, which promotes the formation of a dense, glassy protective layer and effectively suppresses smoke generation, collectively improving the material's limiting oxygen index and smoke density rating.

[0073] Comparative Examples 1 to 4 demonstrate the critical influence of specific components and their modification status 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 from the core flame retardant system, eliminating multiple mechanisms including gas phase inhibition, enhanced condensed phase char formation, physical barrier, and phosphorus-silicon-zinc chemical synergy. This results in a loss of fundamental flame retardancy, a lower limiting oxygen index, and an increased smoke density level. Comparative Example 2 lacks zinc borate, which disrupts the smoke suppression mechanism of the glassy protective layer and reduces one flame retardant synergistic pathway, primarily leading to an increase in smoke density and a concomitant decrease in the limiting oxygen index. Comparative Example 3 uses unmodified halloysite nanotubes, retaining the physical barrier effect but lacking the phosphorus-silicon synergistic effect introduced by surface phosphate functionalization. This reduces the stability of the char layer and weakens the flame retardant and smoke suppression effects. Comparative Example 4 uses commercially available zinc oxide nanowires without phosphorus doping and optimized surface properties. This fails to achieve phosphorus-zinc synergistic catalytic char formation, and poor dispersibility weakens the physical reinforcement of the char layer, similarly leading to a decrease in flame retardancy. 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 collectively demonstrate that the flame-retardant and smoke-suppressing effects of the present invention depend on the synergistic effects of four components: aluminum diethylphosphinate, phosphoric acid-functionalized halloysite nanotubes, phosphorus-doped modified zinc oxide nanowires, and zinc borate. The absence of any key component, as in Comparative Examples 1-2 and 7, or the suboptimal state of a key component, such as the use of unmodified or undoped alternatives in Comparative Examples 3 and 4, disrupts this sophisticated synergistic mechanism, preventing the effective establishment or connection of multiple flame-retardant pathways. This compromises the quality and stability of the condensed-phase carbon layer, as well as its gas-phase suppression effectiveness, ultimately manifesting as a deterioration in the limiting oxygen index and smoke density rating.

[0075] Test Example 2

[0076] Test objects: The polyester fibers in Examples 1-2, Examples 4-5, and Comparative Examples 5-6 were tested.

[0077] Test method: The breaking strength and elongation of polyester fibers were tested according to GB / T14464-2017. The final test results are shown in Table 2.

[0078] Table 2 Mechanical properties test results

[0079] serial 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] As shown in Table 2, selecting a PET resin within a specific viscosity range lays the foundation for fiber strength. The subsequent drafting process, particularly the setting of the total draft ratio, is a key step in inducing high molecular chain orientation and achieving high strength. The synergy between these two ensures that the potential of the matrix material can be transformed into excellent final fiber mechanical properties through optimized processing.

[0081] Comparative Examples 5 and 6 mainly verify the importance of compound toughening agent systems for improving the mechanical properties of high-filled fibers. Comparative Example 5 does not add toughening agent at all, making the polyester matrix extremely brittle and hard in the presence of a large amount of solid fillers. The filler particles become a serious stress concentration source, causing the material to easily undergo 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. Comparative Example 6 uses only a single component ethylene-methyl acrylate-glycidyl methacrylate as a toughening agent, lacking maleic anhydride grafted ethylene-octene copolymer elastomer and its reactive compatibilization synergistic effect with the former. This results in the toughening phase having a less uniform dispersion and interfacial bonding strength with the matrix than the compound system, weakening the ability to passivate filler stress concentration, and limiting matrix toughness, ultimately manifesting as an elongation at break lower than the embodiment using a compound toughening agent, while limiting the potential for the fiber to reach optimal strength under high-ratio stretching.

[0082] These two comparative examples together confirm the necessity of using a compound toughening agent and constructing a strong and tough matrix through reactive volume expansion in the present invention. Comparative Example 5 illustrates 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 by the present invention can more effectively improve interfacial compatibility, dispersion morphology and stress transfer through molecular-level synergy compared to a single toughening agent, thereby providing a key material foundation for subsequent strength improvement and good elongation maintenance through optimization of the stretching process. Without this synergistic toughening, even with the same stretching treatment, it is difficult to achieve the ideal level of mechanical properties, which shows the importance of the synergy between material composition and processing technology on mechanical properties.

[0083] Test Example 3

[0084] Test objects: Fabrics made from polyester fibers in Example 1, Example 4, Examples 6-7, and Comparative Examples 7-8 were washed 10 times and then tested.

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

[0086] Table 3 Antibacterial performance test results

[0087] serial number Antibacterial rate of 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 modified zinc oxide nanowires, including the specific hydrothermal reaction conditions and subsequent surface treatment, determines the morphology, doping state, and surface properties of the antimicrobial core material. Through parameter control, the prepared nanowires work synergistically with the matrix environment to ensure the effective release of antimicrobial ions and the long-term performance of their function, thus realizing the antimicrobial properties of the fiber.

[0089] Comparative Examples 7 and 8 primarily investigated the effects of modified zinc oxide nanowires and their surface treatment on the antibacterial properties of the fibers. Comparative Example 7 directly removed the modified zinc oxide nanowires, which served as the antibacterial core, depriving the fibers of their primary 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 far lower than that of the specially designed nanowires, failing to provide effective antibacterial protection. In particular, the antibacterial rate is extremely low after washing. Although phosphorus-containing zinc oxide nanowires were used in Comparative Example 8, the subsequent KH550 surface treatment step was omitted. According to the present invention's analysis, the surface treatment is intended to improve the compatibility of the nanowires with the hydrophobic polyester matrix, promoting uniform dispersion and enhancing interfacial bonding. The lack of surface treatment can lead to nanowire agglomeration, reducing the exposed effective antibacterial sites. More importantly, weak interfacial bonding forces make the nanowires easily detached during washing or use, resulting in a decrease in the durability of the antibacterial effect and a significant reduction 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 function. Comparative Example 8 emphasizes that simply introducing antibacterial substances is not enough. It is necessary to use auxiliary means such as surface treatment, combined with matrix volume expansion and precision processing to ensure the stable presence and effective distribution of antibacterial agents in the fiber 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 ultimate antibacterial performance.

[0091] Test Example 4

[0092] Test objects: 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] Table 4 shows that controlling the size of halloysite, zinc oxide nanowires, and zinc borate, in conjunction with screw speed control in both the main extrusion and masterbatch extrusion processes, optimizes melt flow and shear dispersion. The combination of precise particle size control and appropriate processing shear effectively improves the dispersion uniformity of highly filled systems, thereby ensuring stable processing and uniform final fiber quality.

[0098] Comparative Examples 9 and 10 focus on verifying the crucial role of the preparation process, particularly masterbatch pre-dispersion and particle surface treatment, in the processing stability and final product uniformity of highly filled complex systems. Comparative Example 9 uses a one-time blending process instead of a masterbatch pre-dispersion process. However, due to the limited mixing time and shear strength of the main extruder, which is insufficient to effectively break up the high-content, multi-type nano- and micro-filler agglomerates, the dispersion of the material is extremely uneven. This unevenness directly leads to problems such as melt viscosity fluctuations, unstable processing pressure, and easy mold clogging, making the spinning process difficult to carry out stably. The final fiber has poor strand dryness, inconsistent performance, and an overall decline in overall performance. Comparative Example 10 also omits the surface treatment of two inorganic fillers, zinc oxide nanowires and zinc borate. This results in extremely poor interfacial compatibility between the filler and the organic matrix, not only exacerbating the filler agglomeration problem but also forming 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 a deterioration in overall performance.

[0099] Comparative Example 9 demonstrates the role of masterbatch pre-dispersion in overcoming dispersion challenges and ensuring uniform dispersion in the preparation of highly filled nanocomposites. Comparative Example 10 emphasizes the essential role of particle surface modification in improving interfacial compatibility between inorganic fillers and organic matrices, stabilizing the processing process, and ensuring final material properties. Overall, the synergy of particle surface treatment, compounding and toughening, masterbatch pre-dispersion, additive formulation, and precise process control effectively addresses the processing challenges of highly filled, complex systems, achieving a balance between functionality, performance, and manufacturability.

[0100] While 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 these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A flame-retardant and antibacterial dual-functional fiber, characterized by: Calculated 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 pretreated zinc borate; the pretreated zinc borate is obtained by surface-treating zinc borate with KH550; The raw materials for preparing the modified halloysite nanotubes include halloysite nanotubes, KH560, and phosphoric acid; The raw materials for preparing the modified zinc oxide nanowires include zinc nitrate hexahydrate, hexamethylenetetramine, sodium hypophosphite, and KH550; 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 according to claim 1, characterized in that: The preparation method of the flame-retardant and antibacterial dual-functional fiber is as follows: S1: Mixing the composite modifying agent masterbatch, PET resin, and composite toughening agent, and then feeding them into a twin-screw extruder, and then melting, extruding, cooling, and pelletizing to obtain modified PET resin; 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. and extruding it through a spinneret to form a thin melt stream, which is then solidified in a cooling air flow at a temperature of 25° C. and a wind speed of 0.9 m / s to obtain spun fibers; S4: drawing the as-spun fiber, wherein the first-stage drawing temperature is 85° C. and the second-stage drawing temperature is 150° C., and the total drawing ratio is 3.8-4.2 times; S5 is to wind the drawn 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 modification additive masterbatch comprises: stirring and mixing 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, an antioxidant, a lubricant, and the PET resin at a speed of 1000 rpm for 10 minutes; feeding the mixture into a twin-screw extruder for melt extrusion, cooling and pelletizing to obtain the composite modification additive masterbatch.

6. The method for preparing the flame-retardant and antibacterial dual-functional fiber according to claim 5, characterized in that: When preparing the composite modifying auxiliary agent masterbatch, 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 comprises: ultrasonically dispersing 10 parts by weight of halloysite nanotubes in 100 parts by weight of anhydrous ethanol to obtain a suspension A; adding KH560 and deionized water to the suspension, wherein the amount of KH560 added is 8-10% of the weight of the halloysite nanotubes; stirring and reacting at 70°C for 4-5 hours, filtering, washing and drying the solid to obtain epoxy-modified halloysite nanotubes; dispersing the epoxy-modified halloysite nanotubes in N,N-dimethylformamide to form a suspension B; and adding 4.5 parts of a 75-85% by weight phosphoric acid aqueous solution to the suspension B, stirring and reacting at 70°C for 4.5 hours, filtering, washing and drying the filtered solid 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 modified zinc oxide nanowire preparation method comprises: dissolving 14-16 parts by weight 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; reacting the precursor solution in an autoclave at 120° C. for 7-9 hours to obtain a reaction solution; cooling the reaction solution and centrifuging to obtain a precipitate; washing and drying the precipitate to obtain phosphorus-containing zinc oxide nanowires; and adding the phosphorus-containing zinc oxide nanowires to anhydrous ethanol and ultrasonically treating the solution for 30 minutes to obtain a dispersion. 3-4% by weight of KH550 containing phosphorus-containing zinc oxide nanowires was added to the dispersion, and the mixture was stirred and reacted at 60° C. for 4 hours. After the reaction was completed, the mixture was filtered, and the solid was washed and dried to obtain a coarse powder; the coarse powder was ground to obtain the modified zinc oxide nanowires.

Images